The source code for the Picomites is available here. The compiled binaries and documentation are readily available here. If you want to compile your own binary the key information required to compile the code is listed in the readme of the source. In general the developers cannot/don't give support in the setup of the development environment as there are many moving parts and remote support can be very time consuming and difficult.
This post by TBS by member @karlelch contains an example and a detailed instruction for the setup of a Windows 11 environment which may be helpful.
TBS thread with example