Do I have to edit with proxies?

Yes. Your editor can show any frame at full resolution, for example to check focus or detail. But an 8K frame takes a quarter of a second or more to stitch, so full resolution does not play smoothly. So you edit on the small proxies, which play in real time, and full resolution is for checking frames and for the final render. If you want to edit directly on full-resolution footage, this is not the right tool for you.

The proxies come from the low-resolution files the camera records alongside each recording, so keep those files with your recordings. See Proxies and audio.