Hi Patrick,
YARPP supports posts and pages, and standard post categories and taxonomies.
-Use the same post Category or Tag for the similar post and pege
-Set in YARPP settings taht Categories and Tags to be considered
-Set “Post types used by WRI” for Posts and Pages in WRI settings.
-Go to “Pages Page” tab (because you would like to display related items on Pages), in Posts row (because you would like to display posts) set an appropriate (not too high e.g. 1 or 2) match threshold, select “Bottom of Page” in the Position field (or you None or just widgets if you want display items in widgets)
-The go to YARPP settings page and save YARPP settings (it is refresh all YARPP settings)
-If you want to display related items in a widget, then place “WP Related Items (WRI)” widget in the sidebar, and chose “Posts” in the Related Post Type field, because you would like to display related post.
You can find more details here in the FAQ tab: https://webshoplogic.com/product/wp-related-items-pro-wri-wordpress-plugin/ (for Lite and Pro version either)
Using these settings, the related pages should be displayed on your posts.
Best Regards,
Peter Rath
WebshopLogic