I am experiencing the same issue as the one listed below which doesn’t seem to have a resolution (and I couldn’t add my comments there). When I click a Dropbox link in Facebook
Messenger it gives me a message “get the app or continue to the website”. It also states it will pass a link to the file, across to the app. I already have Dropbox installed so I’m not sure why it isn’t doing this anyway. If I click got to the app it takes me to the App Store which shows that Dropbox is already installed and only has the “open” option. When I click open, it opens my Dropbox but doesn’t bring the file in question.
Here is the original issue raised regarding this.
https://www.dropboxforum.com/t5/Dropbox-files-folders/I-have-an-issue-with-shared-links-and-Facebook-s-messenger-Any/m-p/434805
Thanks