How to open Strongbox database stored in family room of Dropbox

I currently use Strongbox to store passwords on three of my devices and I share the file with my wife who uses it on her three devices. I email the file to her and then download the file into Strongbox on her devices.  So essentially we each have a local copy of the file.  I am trying to put the file into the cloud for security reasons and so that we are working from the same database and won’t have to email a new copy of the database every time there is a change.

I “chatted” at length online yesterday with a Dropbox rep who told me this could be done with Dropbox Family.  So I purchased the Dropbox plan and created a test Strongbox database and in the Strongbox app I then chose to store the database in Dropbox.  I sign into Dropbox on any of my and my wife’s devices and can see the test file in the Dropbox family folder.  But I cannot open the file.  It says the .kdbox files can’t be previewed.  I can’t seem to find a way to open the file in Strongbox.  I can copy the file, but then changes aren’t saved to the original file stored in Dropbox, which defeats the purpose.

I would appreciate any help.  (Sorry my post is so wordy…)

Thanks.