files

If you are looking for Documents stores in iCloud, you can use built in Files App which now takes the place of the old iCloud App on iPhones.

Use the Files app on your iPhone, iPad, and iPod touch - Apple Support

What documents are you looking for on your SE?

As far as iCloud icon is concerned, go to Settings, 1st option (your name), Apple ID, ITunes&Appstore.

To access it on your computer, go to www.iCloud.com

Regards

Giulio