Q: I downloaded an app from internet FinalCuTX Server to control with my ipad my final cut pro x, but after I downloaded the app my keyboard left working, and the app says that I have to enable assistive devices, I tried but still not working

I downloaded an app from internet FinalCuTX Server to control with my ipad my final cut pro x, but after I downloaded the app my keyboard left working, and the app says that I have to enable assistive devices, I tried but still not working, so I don't know how to enable my keyboard again