Need to upgrade plan?

We have the doorbell and recently bought another camera for our backyard. It worked initially for the first few days (being able to see live camera, motion alerts, etc), but now only the doorbell works like this. Whenever trying to go live on the second camera, we get an error message saying it can’t connect. We have the basic plan. Is the fix for this as simple as upgrading plans to the next one to get the new camera to work, or is there something else that needs to be done?