You basically have two types of users - an admin person and a Point of Sale (POS) user. Your users can have access to either section or both. Simply add their email address on the right and tick the relevant sections you want them to have access to.
An admin person has access to everything apart from the POS section and a POS person can only access the POS section.
You can tick both if you want the user to have access to both section. Now click ‘Send Invitation’. This will send them an email and ask them to create a password to log in to your shop.
Once logged in, users can manage multiple shops using the same username / email address.