User ID to Airtable & Lemon Squeezy

Hello all!
I create a random USER_ID (number) in Airtable and I’d like to know if there is a way to march it with softr. Or if softr creates this ID and I can pass it to airtable somehow while signing up. When I check the sign up form, and create a hidden field, the only option I see are these:

Not sure if that work out, but I don’t know how to approach it.

Also, I am trying to use lemon squeezy as a payment gateway, so ideally, I would like to pass the USER_ID to the payment platform so when purchase is completed I could easily match it with my user. I have seen it is possible to do it by email, however, that could lead to some trouble if user does not use the same email.

Can anyone throw some light here?

thanks a lot in advance!