Initial file for Ant

I would like to study the source code for YaCy, a peer to peer open source
search engine. On their GitHub, it details that the tool is built from
source with "ant clean".

I looked through the YaCy project repository but I wasn't able to pick out
which initial file ant would look for to begin a configuration, building
and installation procedure, analogous to the command "make" looking for a
makefile.

Is there a specific file ant looks for? Or does it work a different way?

Thanks very much,
Julius