Hello shidafrombern,
Thanks for that info and for choosing the Apple Support Communities. If we understand correctly, you are unable to access iCloud mail in the Mail app on your Mac. To make sure this is setup correctly, let's make sure you are signed into your Apple ID on your Mac with these steps:
"Set up iCloud on your Mac
1. On your Mac, do one of the following:
* macOS Ventura: Choose Apple menu
> System Settings, click [your name] at the top of the sidebar, then click iCloud on the right.
* If you don’t see your name, click Sign in with your Apple ID, enter your Apple ID and password, then click iCloud.
* macOS 12 or earlier: Choose Apple menu
> System Preferences, click Apple ID, then click iCloud.
* If you don’t see Apple ID, click Sign In, enter your Apple ID and password, then click iCloud.
6. Turn on or select each app or feature."
Then make sure iCloud Mail is enabled for iCloud in this window. And that info is from here: Sign in to iCloud on all your devices - Apple Support Then quit and re-open the Mail app and see if you are able to access your iCloud Mail again. If not, please let us know any error messages you are seeing and any additional details that could be helpful.
Cheers!