Setting up a second protect basic plan

Hi there I bought a floodlight a few months after my doorbell, the doorbell is set up on a ring basic protect plan, can I add a second basic plan for the floodlight or do I need to get the plus? I can’t see how to get the basic on the website for my second device? My trial for the second device is almost up; but I’d already subscribed to the first plan for the doorbell Any help please?