MIDI controllers not recognized in iPad's Garageband.

iPad OS is 18.5. I have a USB 2.0 cable from Amazon Basics going from my keyboard's USB-B port (Yamaha PSR-EW 300) to my iPad's USB-C port. I'm trying to connect the keyboard to use virtual instruments in Garageband, but the keyboard doesn't seem to be recognized. I can tap on the screen to play the instruments still. I tried connecting the iPad to another keyboard (Akai MPK Mini) & got the same result, so I'm guessing it's an issue with the app or iPad...