Not able to Sign in to iPhone Adobe Reader App- Blocked by strange pop up

I cannot sign in to my ADOBE app on either of my iphones as a pop-up appears asking me to confirm sign-un account. When I try to sign in, it gives me a weird email = my regular email with the word "old" added after the .com.

WHen I try to sign in, the system blocks me by asking to VERIFY YOUR IDENTITY.

It asks:

"enter the code we just sent to (my email address).old.

And of course, I cannot receive the code as my email address is .com and NOT .com.old. 

Apparently, ADOBE created that weird email .

What can i do?