Awesome Martin, this will be a good link to send people who are having issues.
Verification Process

Do you have to be a diamond chess.com member? Hope not! Thanks!
Nope, just a USCF member.

Also, are these ratings separate from your actual uscf rating? Because what if you are 1600 for blitz uscf and 1900 for blitz on chess.com? How does that work?

Also, are these ratings separate from your actual uscf rating? Because what if you are 1600 for blitz uscf and 1900 for blitz on chess.com? How does that work?
These tournaments use chess.com ratings for pairings, and USCF rates it afterwards. The c.c ratings and USCF are separate.

If you filled it it by Thursday and were already a member of the group, then you are fine. We remove problem accounts from the group after each day's verification by the USCF and send out a message to fill out the form again and rejoin.

3. Get verified by the the USCF
The USCF will be verifying form dataModified some wording; USCF will try to do each weekday but it may not be every day.

The verification link (https://www.chess.com/news/uscf-member-authentication-9266) is returning a 404 error.

That link only works in v2 of the site; apparently something changed. I'll update with the following, which works in both versions.
https://www.chess.com/news/view/uscf-member-authentication-9266

I think I'm good to go. For whatever reason, it seems I was already a member of this group, but I don't remember applying to join o_O . I filled out the form about 20 minutes ago. Is it feasible that I can play in this Friday's tournament?
Here is some information on how the whole process works to tie Chess.com accounts to USCF ones.
1. Fill out the USCF Authentication form: https://www.chess.com/news/view/uscf-member-authentication-9266
2. Join the US Chess Members Only group: https://www.chess.com/club/uschess-members-only
3. Get verified
4. Keep your USCF membership current; if your membership expires you will be removed from the group. You can re-apply for group membership once you have renewed, but will not need to fill out the form a second time.
updated 11/2020