Thanks for asking!
You will need Intiface Central to be running for the mod to work.
For the native connector, download cubutt-native
from the Github releases page, then open up a terminal in the directory you downloaded it to, and run it like ./cubutt-native ws://localhost:12345
(replacing ws://localhost:12345 with the address shown by Intiface, if Intiface is running on a different machine such as a phone)
Intiface should show that a client called CuButt is connected, and any devices you connect to Intiface should automatically work with the game!
Note that Windows and MacOS are currently not supported by the native connector (but may be coming soon?).
Hope this helps!