Google sheet SUM based on criteria of criteria in multiple sheets

On the same Googlesheet document, meant to manage multiple License keys, I've got three different sheets.

First sheet is the list of the Keys. As soon as a key is used, I set its user.

Second sheet is the list of the Users. As soon as I have a new user, I set its name and its role.

Third sheet is the list of the Roles. This is a list of the different roles that needs a key.

Problem : On the third sheet, I'd like to count how many keys are used for each role.

Example : I'm Paul, I'm UX Designer, and I use one key.

On the first sheet, one key is set to my name. On the second sheet, my name is set to the role UX Designer.

I'm basically the only UX set with one key. So, on the third sheet, it should count 1 as the number of key used by the role "UX Designer".

Many thanks in advance, I hope I was clear !