If you want to see clients who have never signed up for a membership, you can find them using the Clients Without Memberships report.
To access this report:
Go to the left-side menu > Reports.
Go to the Membership tab
Select Students Without Memberships.
Note: This report is based on students who are actively training under a membership. If a student has a membership that has not started yet or has already expired, they will not appear on this report.