Setting up a Sharepoint Online Image Gallery

[CestM0i]

I think the best way to describe my troubles is to post a couple of screenshots. I'm trying to add an Image Gallery to a site page that links to a folder, so that when a new image is added to the folder it also gets added to the gallery.

 

According to guides online I should see this (with an option to choose a source folder):

 

Unfortunately, I am seeing this (and ahead of any queries I can't follow the add image link and just select the folder rather than specific images):

 

Hopefully there's a tick box somewhere that someone can point me towards. Any help appreciated