As on a name, this is the main primary page for Flexi to work. All the links (tags, search, categories, detail) refers to this page. If this page is absent you may lead with 404 error pages.
This page is automatically created and linked to Flexi setting. If it doesn’t exist you have to create a new page and add the content as [flexi-primary] . You can keep any title of the page and can change anytime but do care of it’s slug name. You may loose search engine submission, if it is updated.
Things to note for this pages as below
Do not add extra attribute to [flexi-primary]. Try to use Flexi settings.
Do not make this page as front page of your site, it may lead to wrong page reference.
If you want to use it in front page, use [flexi-gallery] as a shortcode but do not link it as primary page at Flexi settings.