Connecting pre-existing simplicam to new 5G version of SS

I purchased the 5G version of SS and replaced all components except the simplicam cameras (according to the purchase instructions new cameras were unnecessary - the old ones would work). I've been unable to connect the two indoor cameras. The new doorbell camera connected right away. I removed the indoor cameras from the account along with all of the old sensors assuming I could do a fresh install. I've tried at least a dozen times to connect each of the two cameras and nothing works.  Any insights are appreciated.