Each person turns it on in Settings → Two-step login and scans the code with an authenticator app (Google Authenticator, Microsoft Authenticator, Authy, 1Password).
After the password, TotalBay asks for the 6-digit code. Trust this computer for 30 days skips it on that browser.
Save the 10 backup codes. Each works once.
The owner can require it for admin logins and reset someone's lost phone.
The shop desk key login never asks for a code, so the front desk can't be locked out.