Vlookup link to unshared file in Dropbox

Hello, 

I have a "master file" that is not shared on Dropbox. The master file cannot be shared due to sensitive info.  

I need to share a 2nd excel Macro file (lets call it File #2) in Dropbox that has a vlookup to the "master file" and return values if the data is the same. 

I have actually done this in the past and even though the path was not the same for the users, it worked fine. That is no longer the case and I need help how to make this work please. 

VBA is not an option as File #2 already has a VBA coding and my knowledge is very limited any other suggestions welcome :)