Managing personal Outlook.com account settings, security, and privacy
Hi Steven,
If you've previously saved the password in your browser, you may be able to view it in the browser's password manager:
Microsoft Edge: Settings > Profiles > Passwords
Google Chrome: Settings > Password Manager
Firefox: Settings > Privacy & Security > Saved Logins
Or you may also try to check from your iPhone's passkey if it was saved in there.
But to further assist you with this, are you trying to setup your icloud account to the outlook application where it keeps asking for a password?