Hi Ben,
It looks like the USB focus motor is the best to go with as its ASCOM compliant so you can do auto-focus with SGP. (You just have to decide whether you want the 4.5Kg version or the 1.5Kg version).
As to whether you need that focuser adapter kit you linked, I'm not sure, the description says its for a Newt focuser.
There is another focuser adapter kit called steeltrack which may be the correct one.
https://www.teleskop-express.de/shop...k-focuser.html
I would send an email to teleskop-express and ask for their advise.
Cheers
Bill