Reinstalling free version instead of pro

I purchased pro in 2014 but really didn’t need the extra features (I’m retired). I am trying to get a new computer up and running but after the hassle of being told my computer was not going allow me to send emails any longer because I hadn’t renewed my license (and therefore was running a newer version than I had before) I went on and checked deactivate. But now when I try to go on and apply for a free version it says my email address already has an account and therefore I can’t apply for a free license. Can I downgrade without uninstalling? Will reinstall even work since I’m not changing my email?
Any suggestions would be appreciated

P.S. As soon as I deactivated the account it quit showing
new emails. I am now on my phone to check email. Thanks