Selecting categories in the admin

Upgrading a website from 2.11 to 5.1.1 i run into trouble. There is a catalog of documentation which are categorised using EE categories. Product pages who link to this documentation using a plugin called WB Category Select (selecting what categories of documentation that should be shown under each product) Not being able to use this plugin anymore how do i in the admin on the product page select what categories to display? Wes Baker did this so beautifully using a drop-list.