The first issue you have is activating windows on the new PC. You can try entering the same product key you used before (see link below), but this may fail if you have an OEM license that isn't meant to migrate to new hardware. You can try the activate-by-phone option, though, as sometimes that will succeed when online activation fails.
Link to very good Windows Key display utility:
https://github.com/Superfly-Inc/ShowKeyPlus/releasesAs your hardware on your new PC is completely different than the old one, if you were going to do a clone of everything to different metal you would need a paid version of hard drive backup software to do it - I have tried it with a free version and it just doesn't work.
You will appreciate your new computer more with a fresh install of Windows 10 20H2, as it will be much more responsive and snappy without all the old drivers & clutter dragging it down, doing a clone you would end up with thousands of files that do not need to be there.
You can put your old drive in your new PC temporarily to transfer documents, photos, music etc, just back up everything you can first such as bookmarks / favourites and passwords on your old PC before you take the drive out.
