Filter collection with checkboxes (display only active projects, only quotes...)

My issue is different from this one: Checkboxes within a collection list
I have a Projects collection which includes the delivery date, quote true/false, deleted true/false, etc.
The collection is by default filtered on the frontend with Delivery date is empty.
I’ve inserted a Multi Select element with options for these three (and more) criteria.
How can I filter the collection using the selected option?
I could not find out how to use the value of the selected option in a filter. I tried using the Apply if condition but this seemed to work only for one selection (I combined the options in the filter using OR + Apply if). However, the filter should work differently according to the selected option (only one criterion can be selected at a time).
Of course I could create different collections for each criterion but that’s certainly not the best solution.

I found the solution, even for filtering on the backend since the value of the multiselect (if any) is available as a variable for the collection filter. I think the main issue was that I combined the conditions using OR instead of AND. I’m now also filtering out all deleted (marked for deletion) records by default.