Here are the steps to install rtpMIDI on companion-pi (or any Linux SBC)
Install Companion Pi (or your favourite SBC distro) and get to a terminal window.
At the prompt, enter:
wget https://github.com/davidmoreno/…
Some how-to videos on using Companion v3 and the RCP module.
Just starting out on these, and I plan to do more, based on whatever people are asking about.