Question: How to RUN the program

[Exaeta]

Compiling works fine, but I get the "can't load default.cfg" error.

Where do I take what and copy it where?

[bmillwood]

You need data files which aren't included in the source. Downloading the relevant stuff at http://tremulous.net/files/ and then replacing the binaries with the compiled ones is a good place to start. (You may need to make pk3 files of some of the stuff in assets/, I forget the exact details)