Well the name is confusing to begin with. Gallery makes it seem like you can upload pictures to it.

All the other social medias also use the Gallery profile tab to show all the pictures your profile has uploaded. Should be called favorite pics or something related.

Where it says Empty feed you could also explain to users how to add favorite media to the gallery.

And the Add to Gallery is hidden. Maybe beside the download button out another button called "Add" or a plus symbol. (+)