Since you said you’re using a Raspi4 which is arm64, you’d want the arm64 one I believe. Sorry, I don’t have a RasPi4 to test myself. If that doesn’t work, try the arm32 version.
Honestly, that’s the easy part. The harder part is configuring Wireguard and udp-proxy-2020. This thread will likely help you some, but it’s for Ubiquiti USG and not a RasPi running linux: How to: Roon Mobile over WireGuard on a UniFi USG
Sorry, I don’t have a fancy GUI or super-easy install mode for this… as you can tell, there are at least a dozen different configurations people are using and they’re all different.