Hello urban camel,
It sounds like you're running into an error when trying to access or use third-party apps in Files, correct? We'd like to see how we can help.
"The Files app lets you add your third-party cloud services — like Box, Dropbox, OneDrive, Adobe Creative Cloud, Google Drive, and more — so that you can access all of your files on all of your devices. The files you keep in iCloud Drive automatically appear in the Files app, but you need to set up your other cloud services to access them in the Files app too."
Just to clarify, did you add those third-party apps to Files using the exact steps outlined in the "Use third-party apps in Files" part of this page? Use the Files app on your iPhone, iPad, or iPod touch
If you did use those steps, and you continue to run into an error, please check out the "If you need help" part of the above link as well.
Take care!