Create a ini File in your Project in /Config called “DefaultEditorPerProjectUserSettings.ini”
Include following Parameters
[/Script/UnrealEd.ContentBrowserSettings]
DisplayCollections=True
Either delete your Saved Folder if your sure (You lose for instance Autosaves) or go the save route by deleting in Saved/Config the “EditorPerProjectUserSettings.ini” (You lose your custom Editor Settings, such as Content Browser Thumbnail Size, so save it), to test it if it works.
Now upload the DefaultEditorPerProjectUserSetttings.ini to your preferred Source Control. For existing Users it won’t change anything, assuming that they were instructed to activated it in the Editor directly, but for new users they will see the Collection Tab.