You can grab the binaries from our repo https://github.com/muecoin/MUE/releases/latest
or cross compile the source for a raspberry pi, or even download a fully functional pi image from https://github.com/muecoin/Raspberry-Pi-Images

I would not recommend building directly on a pi, but you can do so if you really really want to.
But, for building, you need to first build all dependencies and then build the source with said dependencies, not whatever you have on your distro: eg the wallet wont compile with openssl 1.1 etc.

I recommend you to get the official binaries rather then building on a raspberry pi.