Hello @Laurenanne! Take a look at Tom's Best Answer in this thread. You can use Employee Management to enable passcode access for your renters and track their retail sales. You don't need to use Square Payroll, unless you're paying someone a wage.

However, if your renters have their own Square accounts you can sign out of your Point of Sale and they can sign in with their account details. There's no account information tied to the Square Stand/Square Register (or Square Reader) but it's important that everyone remembers to sign out!