Click on the pencil icon to access the Button Settings (on the button, that you want to filter with). You can also use images, or any other element to trigger the filtering. It doesn’t have to be a button module.
Go to Advanced → CSS Class. Here you add the ef-button class.
Additionally, add any category that you want to filter with that button like that: efc-[your category] e.g. efc-cats.
Buttons have to be in a separate section, than your filterable elements. Or you add the df-buttons class to your button row (Premium features).
Click on blue icon to access the Section Settings.
Go to Advanced → CSS Class. Here you add the ef-area class.
Click on edit column icon to access the column settings.
Go to Advanced → CSS Class.
Here you add all the efc-[your category] class you want e.g. your efc-cats class.
Do that for all Columns you want to make filterable.