Within Qwil Messenger, your contacts are made up of people you share Client teams with. This is a handy way to ensure your clients' and staffs' privacies are respected.
If you cannot see clients in your contact list, the most likely reason is that you are not in a client team with them. As a User Administrator you can click on the Administration Tab and then click Client Teams to find the relevant client team and enter them.
Another reason may be that your clients have not yet accepted their invitations. You will have to wait till your clients accept to see them in your contacts. To check if this is the case, navigate to the Administration Tab and click on Clients. You will see a list of all active clients. To see pending clients, simply change the dropdown from "Active" to "Pending".