I have tried the above options, but not being too computer savy, some I didnt get. I tried the homebrew option, but terminal says an error occurs when trying to install. I need this 1 file for a work project.
KyngChaos offers its version to include in its GDAL framework, see New GDAL FileGDB Plugin.
The plugin installs ogr_FileGDB.dylib. After that, you must download the FileGDB API, because of the Esri's export restrictions, and move 2 .dylib files to /Library/Application Support/GDAL/1.9/Libraries.