Trying To Re-install (re-sync?) Phone Link To Win With Android..?

Not sure where to begin now.

I have a ProtonMail account that allows two (at least) different addresses which will deliver to (or from?) the same 'main' address (one address ends "@protonmail.ch", the other ends "@pm.me" - however, again, they are the same account.

Somehow, I seem to have transposed them when setting-up a "new" (to me) WIN10 (Home) machine.

This confusion is now preventing me from being able to get the desired phone/WIN sync (due to my limited knowledge [and forgetting] of Windows as well as having worked almost exclusively with Chromebooks the past few years).

Anyone here able to assist? Thx in advance..