Dynamic ID into API call

I have a dynamic value named [ID] in my API call for ActiveCampaign.
I am creating a user page, where I want to add the data I retrieve from this API call.
In the URL of the page, I add the ID. So the URL is: https://www.appname.nl/version-test/newsletter/7525?debug_mode=true
How can I get the number 7525 into the API call? I can’t figure it out. I think it should be rather simple, I did read all kind of posts. But can’t find an answer.

API

Action
Schermafbeelding 2022-04-07 om 17.50.09

Remove private checkbox for your parameter

thanks a lot!