Link categories to project expense types

Summary:

I am looking for a way to connect project expense types to purchase categories for requisitions with a project.

Content (required):

Here is what I am trying to achieve: when entering a requisition with a project, the expense types choice should be restricted based on the category selected earlier.

To achieve this, I added a DFF on Manage Expenditure Types page that displays the list of categories, and mapped every expenditure type to a category.

It seems like there is another setup still missing, because right now, regardless of the category selected, I am seeing all expenditure types instead of only those mapped to the selected category.