Paid Registration

Hi There

I am aware that UM does not have paid membership funtionality ala
https://docs.ultimatemember.com/article/212-does-ultimate-member-have-paid-membership-functionality

My question is if I create a registration form with say Ninja form and Paypal function and was able to set the group they belong to – would I need set anything else in order to work with Ultimate Membership?

Also, I guess if I create custom fields such a interest or postal address. Could I access those from UM profile forms

Thanks

The page I need help with: [log in to see the link]