Steinberg UK22 mkII Connection to MacBook

Hello,

I own a MacBook Air with two Thunderbolt 3 (USB-C) ports, and I need to charge the MacBook Air while having an external hard drive and a Steinberg UK22 mkII external audio interface connected (I want to buy a USB Hub).

The manual for the audio interface says that the cable that came in the box must be used, and also that it must be connected directly to the PC.

Is this true? Do I have to leave one free port directly to the PC for the audio interface?

And an extra question, do I have to use the cable that came purely in the package (USB-A/B) or can I purchase one (USB-C/B)?

Thanks.