AccessPlus is a UT2004 administration mutator. It is based on AdminPlus, adding dozen more admin commands to manage your server.
In order to build AccessPlus you will have to download the source code (https://github.com/EliotVU/UT2004-AccessPlus/archive/master.zip) and save it in your UT2004's main folder, for example in: "C:\UT2004". Once done (it is recommended that you rename UT2004-AccessPlus-master to AccessPlus), you are safe to execute the Make.bat file, the engine will compile the project and if everything was setup right it should compile without any errors.