I can't find the security key thing and therefore I can't get into my email on my new iPhone 8?

I can't find the security key thing and therefore I can't get into my email on my new iPhone 8? - 1

To solve your problem, download the app below and log in to your email through the app. No security key will be required if you do it this way.
App download link: https://itunes.apple.com/...60486?mt=8

Did you, like so many others, fail to port your existing cell number to your new phone. The security PIN will probably have been sent to an old phone number, and if you no longer have access to that number then you may have to get a new email account. I still have the same cell number I got 23 years ago and I have lost count on how many different phones I have had this number.