I have read the article: https://blog.mastykarz.nl/search-engine-optimization-sharepoint-2013/
and several others.
In this part: "SEO Properties for Publishing Pages"
it is explained how to edit SEO properties of a page, we manage to edit SEO properties for folders in sharepoint but when trying to edit a page the "Edit SEO Properties" is greyed out and we can't use it.
We did a test of creating a wiki page template and then the option is available but when trying for published pages which are under custom templates we cannot edit SEO properties.
Do we need to activate some feature?