Much depends on your data model. I'd use three related tables for this, One for your 5 users--one record per user, One for your customers, one for each customer and, if each customer must make multiple payments, a table of customer payments with one record for each payment.
A summary report base on the Payments table can provide you with report with one row for each user and the total payments received for their assigned customers.
But this approach assumes a set of tables that you may not have.
And if customers make one and only one payment, we can do this with two tables rather than three.
Wow...thanks so much...I wish I was more knowledgeable to do that...that seems it would solve my issue
Then please feel free to ask more questions.
Please note that my previous response includes a question:
Do you need to record multiple payments from the same customer?
If you answer that question and then follow up with more questions about how to work from the resulting set of tables and relationships. I and other community members will be happy to work with you on this.