DBExpress for Mac 64-bit

I'm new to Delphi and I'm trying to switch over an app from C++ Builder so I can build a 64-bit Mac app. 

I'm connecting to a Postgres database through Devart DBExpress. Everything's working fine on Windows and on Mac for 32-bit, but I can't get it to build for 64-bit. 

The "DbxDevartPostgresSQL" in my uses clause is being highlighted 

and I'm getting the error Unit 'DbxDevartPostgreSQL' not found.

However, this is not an issue when I switch platforms (the unit is no longer highlighted and the app compiles without errors), implying that the needed files do exist but somehow Mac 64 isn't finding them? Any ideas here? Excuse me as I do not know much about Delphi yet, I only have experience through C++ Builder :) 

(I'm using Delphi 10.3.3, Community Edition)