I followed the instructions on the github readme and got an error. Have I missed a step or something? I downloaded a virtualbox image of centos, ran the two yum steps, and the two git steps, created the OpenPetra.build.config file, then nant as follows:
$ nant generateSolution
NAnt 0.92 (Build 0.92.4543.0; release; 6/9/2012)
Copyright (C) 2001-2012 Gerry Shaw
http://nant.sourceforge.net

Buildfile: file:///home/vagrant/openpetra/OpenPetra.build
Target framework: Mono 4.5 Profile
Target(s) specified: generateSolution 

     [echo] operating system=Unix 3.10.0.957
     [echo] platform=unix
    [mkdir] Creating directory '/home/vagrant/openpetra/tmp'.
  [include] Including file /home/vagrant/openpetra/OpenPetra.build.config.
    [mkdir] Creating directory '/home/vagrant/openpetra/log'.
    [mkdir] Creating directory '/home/vagrant/openpetra/var'.
     [echo] Running on Unix
    [mkdir] Creating directory '/home/vagrant/openpetra/delivery/db'.

minimalGenerateSolution:

     [echo] Target minimalGenerateSolution started at: 11/23/2019 21:25:47

generateTools:

     [echo] Target generateTools started at: 11/23/2019 21:25:47

nanttasks:

     [echo] Target nanttasks started at: 11/23/2019 21:25:47
     [nant] /home/vagrant/openpetra/inc/nanttasks/nanttasks.build compile
            Buildfile: file:///home/vagrant/openpetra/inc/nanttasks/nanttasks.build
            Target framework: Mono 4.5 Profile
            Target(s) specified: compile 
            
              [include] Including file /home/vagrant/openpetra/OpenPetra.build.config.
            
            custdepend:
            
                  [csc] Compiling 9 files to '/home/vagrant/openpetra/delivery/bin/Ict.Tools.NAntTasks.dll'.
            
            compile:
            
            
            BUILD SUCCEEDED
            
            Total time: 1 seconds.
            
     [echo] Target nanttasks finished at: 11/23/2019 21:25:48
     [echo] Starting GenerateNamespaceMap at 9:25:48 PM
     [echo] Completed parsing 491 files at 9:25:49 PM
     [echo] Completed NamespaceMap (232 items) and DllMap (11 items) at 9:25:49 PM
     [echo] Finished GenerateNamespaceMap at 9:25:49 PM
     [nant] /home/vagrant/openpetra/csharp/ThirdParty/ThirdParty.build compile
            Buildfile: file:///home/vagrant/openpetra/csharp/ThirdParty/ThirdParty.build
            Target framework: Mono 4.5 Profile
            Target(s) specified: compile 
            
              [include] Including file /home/vagrant/openpetra/OpenPetra.build.config.
            
            compile:
            
                 [echo] Target ThirdParty compile started at: 11/23/2019 21:25:49
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 2 files to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 2 files to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 5 files to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 1 file to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 2 files to '/home/vagrant/openpetra/delivery/bin'.
                 [copy] Copying 3 files to '/home/vagrant/openpetra/delivery/bin'.
                 [echo] Target ThirdParty compile finished at: 11/23/2019 21:25:49
            
            BUILD SUCCEEDED
            
            Total time: 0.5 seconds.
            

generateProjectFilesInternal:

     [echo] Target generateProjectFilesInternal started at: 11/23/2019 21:25:49
     [echo] Target generateProjectFilesInternal finished at: 11/23/2019 21:25:49

quickCompile:

     [echo] Target quickCompile started at: 11/23/2019 21:25:49
compiling OpenPetra.Tools
Compiling /home/vagrant/openpetra/csharp/ICT/Common/Ict.Common.csproj
Compiling /home/vagrant/openpetra/csharp/ICT/Common/IO/Ict.Common.IO.csproj
/home/vagrant/openpetra/csharp/ICT/Common/IO/Csv2Xml.cs(380,47) : error CS1502: The best overloaded method match for `string.Split(params char[])' has some invalid arguments
/home/vagrant/openpetra/csharp/ICT/Common/IO/Csv2Xml.cs(380,65) : error CS1503: Argument `#1' cannot convert `string' expression to type `char[]'
/home/vagrant/openpetra/csharp/ICT/Common/IO/TextFile.cs(258,37) : error CS1502: The best overloaded method match for `string.Split(params char[])' has some invalid arguments
/home/vagrant/openpetra/csharp/ICT/Common/IO/TextFile.cs(258,43) : error CS1503: Argument `#1' cannot convert `string' expression to type `char[]'
/home/vagrant/openpetra/csharp/ICT/Common/IO/TextFile.cs(259,37) : error CS1502: The best overloaded method match for `string.Split(params char[])' has some invalid arguments
/home/vagrant/openpetra/csharp/ICT/Common/IO/TextFile.cs(259,43) : error CS1503: Argument `#1' cannot convert `string' expression to type `char[]'

BUILD FAILED

/home/vagrant/openpetra/OpenPetra.build(354,4):
compiler error(s)

Total time: 5.2 seconds.