We don't currently have a Mandatory payments option, but there is a workaround for groups that want to take a membership payment before allowing access to the group content.
- Set a required field on your registration form with only one checkbox, which acts as a confirmation for the payment (so a field such as 'I agree to pay membership fees of $x.xx').
Change your group's settings to be set in such a way to allow access only to members of a 'List' you create called 'Paid Members' or similar, with everyone else only being able to view the homepage (or any other public pages).
- Create a 'Not yet paid' list with a filter to contain all members who's 'I agree to pay membership fees' databse column contains 'Yes'.
- Create a 'Paid' list on to which you will manually put any member who pays for membership.
- Add a 'Payments' widget to the homepage from the 'Layout' page, with a description informing members that they must pay before being added to a group. You can also e-mail payment requests to members if you prefer.