FORE MIDI to USB Interface MIDI... https://www.amazon.com/dp/B0719V8MX1?ref=ppx_pop_mob_ap_share

That’s the one I got and it’s been great!

Yes you can use something like that and ignore the output connector. Midi out on the keyboard will connect to the midi in connector on the adapter. https://www.amazon.com/FORE-Interface-Converter-Adapter-Laptop/dp/B0719V8MX1/ref=mp_s_a_1_13?dchild=1&keywords=usb+c+midi+cable&qid=1605714471&sprefix=usb+c+midi&sr=8-13

Another probably better option would be to get a class compliant usb c audio interface that also has midi in/out. This way he can interface with the keyboard and also have dedicated outputs for speakers, headphones etc. I previously had a Behringer umc404hd quick worked great, but I know there are a lot of options.