What happens when files are made offline available?
When you mark files or folders to be offline available in the OneDrive mobile app, it means they are saved locally on the device in a read-only state. They can only be changed when there is an internet connection, any edits made whilst offline will create a new version.
Make files/ folders from SharePoint and Teams available offline
You can make files/ folders from SharePoint and Teams available offline on your device in the same way you can files from your OneDrive. Just press the libraries option to see all the “shared libraries” or SharePoint/ Teams sites you have frequently used or followed.
You can navigate through the sites just like a folder structure.