Hi there @AKanan, welcome to the Community!
It looks like the URL in the Secure Documents Public URL field might not be a direct link to the file itself, but instead to view of the file. I say this because the end of the URL doesn’t appear to include a file extension like .pdf which is what I’d expect to see if the URL was a direct link to the file.
Are you able to try testing with a different, publicly-accessible link to the file that contains the file name and extension?
If that goes through successfully then that would indicate that it’s an issue with the URL in the selected Secure Documents Public URL field. And if it doesn’t go through successfully then it might mean that there’s a bug with the Personio app.
Looking forward to hearing from you on this!