Quota groups are required for sending out emails, setting up suppliers and many other functions in the system.
You can set multiple quota groups per project, with different costs associated with the members, and then invite them to their specific groups.
The definitions you find here are:
Country: Which country this quota group is in place for
Name: The Name of this quota group. This will appear as a possible selection, so if you have multiple quota groups for this project, make sure you can tell them apart in the name.
Interviews: How many interviews are required? This will not influence hard stops in the survey, but is more of a note for your records.
CPI: Cost per interview (How much it costs for recruitment)
Incentives: How much is the honorarium to each member who completes this project?
Inc. Admin Fee: How much does it cost to process the incentive per member.
End Date: Around when should the interviews be completed/deadlines. This will not close the project if it goes past the end date.
Notes: Any notes regarding this quota group.
The cost for each member that completes the interview will be CPI+ Incentive+Inc. Admin Fee.