How to link a user to a customer entity.

Hello, we are students and have to create a working mendix web portal,    In this portal, we have to create customers(companies) and assign users to those customers(entity).  We have created a cross-module association from customer to user.  But we have no idea how to link the users to the customers' entity.  Our first thought was to do this with a button that opens a page, and we could select the users using a microflow, but we are quite new to Mendix, so we are completely in the dark about how we should do this. If anyone could help us with this problem, that would be great.  Klant = customers in Dutch   Thank you in advance. (Mendix version 9.11.0)  
1 answers

Edit – (1-1 with Account as I suggested is not applicable – I had misinterpreted your ‘Client’)

You can set the associated objects via reference set selector widget in the edit page for Klant