Apple's Files app is a great tool for organizing and managing your documents, photos, videos and other files from whatever device you are on. When you first start using it you will see that you can save your files locally (on your current device, e.g. your iPhone or iPad) or to iCloud Drive. Of course many of us use third party cloud storage apps like Google Drive, Dropbox, Amazon Drive, OneDrive and so on. These are compatible with Files, but you'll have to link them before you can start using them with the Files app. Here's how to do it on iPhone or iPad:
One of the great features of iOS 11 and later is the Files app. Saving and browsing files directly on an iPhone, iPad or iPod touch now has native support. Not only can files be stored locally on the device, but iOS can take advantage of cloud-based storage solutions such as iCloud or Dropbox. Individual apps can even be configured to use different locations for file storage by default.
Dropbox allows you to grant other people the ability to edit documents in shared folders within both the desktop and mobile apps. Anyone with "edit access" can view, edit and comment on a shared file. All changes made to the file will be shared with everyone who has access to the shared folder. Here's how to grant someone edit access in the iOS app on the iPhone:
To create any Office document in the Dropbox app you need the appropriate Microsoft app installed on your device. Here's a list of compatible Microsoft apps for iOS: