I received the letter from DropBox today and contents of that letter is as follows:
Due to recent product updates, as of April 1, 2018, you'll no longer be able to access your Dropbox files and photos via Gallery or My Files on your Samsung device. Dropbox will also no longer support syncing to the Samsung DocumentSync folder.
Not to worry—your files won't be deleted or modified as a result of this change, and getting to your Dropbox files is easy. To view, upload, or organize your Dropbox files, download the Dropbox app from the Google Play Store.
For more information on this change, please visit the Dropbox Help Center.
- The Dropbox Team
Previously, some Samsung device users could access all their Dropbox files from the Samsung Gallery or My Files apps, or through the DocumentSync folder. These allowed you to add, edit, and delete any files stored in Dropbox without opening the Dropbox app itself. Changes you made would appear both on your phone and in your Dropbox. However, these integrations are no longer available. (Source)