As noted by @JMM.
Also as forwarded in email: The GPS plugin doesn't show as a specific plugin under Settings > Plugins, because it doesn't really have settings. If you go to a page settings > gallery, and look under captions or popup, you will find options to add MAP BUTTON into the captions.
As long as your images contain GPS data, and you have some map buttons enabled somewhere, then map buttons will display like in the demo (see last 3x images):
https://demo.photo.gallery/examples/features/exif/