When I go to 'Add an App' under Site Contents, I do not get a Photo Library as a choice.
I only see Document Library, Custom List, and tasks.
I believe this site was set up as a team site.
Any advice as to how I can add this app as a selection
if it is team site and picture library app not showing, try to deactivate and reactivate the Team Collaboration List feature. Close all browser and open a fresh session.
also try to create a new subsite in the same site collection with team site template and check it their.if failed then try to create a new site collection with team template in same web app and then check the status.