Impossible to sign up

I've been trying to sign up for an account for about a year now. My problem is always the same (see photo). Used to have an Amex, thought that might be the issue, got a Capital on Tap credit card that's a Visa specifically for this and the issue still persists.

The transactions to verify the card in each market go through fine. Has anyone dealt with this? Support haven't been any help at all.