bam 0.4 is missing

i want to compile a source code for a mod that uses bam 0.4 only no cmake i just want to practice coding on it i am a noob idont know anything yet i just want to start understanding how mods work and wanted to try that on a mod i like but i cant find bam 0.4 on github only 0.5+ is there a way to get 0.4 ?