Apify Web Scraper + Make and a place for storage such as google drive should be able to do this.
The free tier of Apify should be enough for weekly 1 csv download, depends if the client portal has anti-scraping measures in place how hard this would be.
It is a bit of a technical solution though.
alternatively, if when you update the parameters, it also updates the URL, you could probably just pass the CSV download URL direct to make, with copied login cookies.