Signing in confirms your identity. Access to a Keystonne OS business is determined by its memberships, roles and other access requirements.
Check that you used the account that received the invitation. If you belong to more than one business, select the correct one in OS. Ask the owner or an authorised manager to review your invitation or membership.
For till access, team roles and operational permissions, use the OS guides. Creating another account or repeatedly signing in cannot grant a missing role.