1. In the configuration > Register User > click on Add user
2. Fill all details of user like name, mobile number, e-mail id
3. After that choose Master from select employment type
4. In the next step choose Admin from login type and then click create.

you may refer to this short video to select a shop

Note: For security reasons, You can only select or view shops thar are alloted to you by the administrator/master/owner.