Static builds of ffmpeg are available from https://ffmpeg.zeranoe.com/builds/ for windows and Mac
You can get linux builds from here https://johnvansickle.com/ffmpeg/
once u get the ffmpeg binary builds. you just need to copy it to the usr/bin folder or just place it wherever u need to use it from. You would then be able to use ./folder/ffmpeg or “ffmpeg -i… ” directly in terminal if u have pasted it into the bin or exe PATH.
The step by step installation can be seen in this video : https://www.youtube.com/watch?v=MoySuC_aiHY