Cannot access my icloud files when OFF of wifi (via AT&T cell) on iphone

I have iphone 11. icloud access to the FILES has stopped working when I am 'in the wild' using my AT&T wireless rather than wifi.

When i click on a file to download and access, i get "YOU"RE OFFLINE. Check your Internet connection then try again".

How do i regain the ability to access my files on my iphone? HELP

The warning:

My icloud settings: