To add a client to your customer’s list, go to Dashboard → Customers. Click the “Invite Customers” button at the top right corner or click the "+" sign along with Customers in Dashboard. Enter their email address in the “Invite People” form. Your customer will get an invitation email and they will be added when they accept the invitation.
Open the app, and below you will see the people icon. Click on the icon, and at the top right corner tap on the “+” button. Enter customer’s email address. You can add multiple customers at one time, and click “Done”. The customer will receive an invitation to your workspace, once they accept it, they will be stored in the Customer’s list.