I've found a couple threads with different options for this, one using R and the other using a Macro... Here's the link to the Macro post https://community.alteryx.com/t5/Alteryx-Designer-Discussions/Reading-password-protected-file-using-... and the R version utilizes the package this How To page now in the community https://community.alteryx.com/t5/Alteryx-Designer-Knowledge-Base/How-To-Read-Extract-password-protec... hopefully one of those will work for you if you haven't already solved the problem.
Cheers!