If you view a document library settings page and “Save document library is a template” is missing try this work around.
Take the document library settings page URL, e.g. http://SharePoint/_layouts/15/listedit.aspx?List=58d3d056… and change listedit.aspx to savetmpl.aspx. Press enter to load the page and you should be prompted to save the document library as a template.
Richard Skinner 
Hi I get “Sorry, you don’t have access to this page” when I change the url?
same
I’m getting the same “Sorry, you don’t have access to this page”. The request goes through for approval and I’m able to approve. But then the same screen comes up again.
It looks like the permissions aren’t being effected immediately 😐