Special character handling and preventing multiple login requests

[FuryoftheStars]

Hi, not sure if this is the right place to ask this, but...

I'm working for a company where we have the need to archive OneDrive (for Business) contents from terminated employees, but the tools provided by Microsoft are lacking for us in this, especially as some of our employees build up tens or hundreds of thousands of files totaling tens to hundreds of GBs. We prefer downloading the contents of the person's OneDrive and then storing it on a local NAS.

I've managed to find a PnP Powershell script online that I've modified some to meet our needs, but there are still 2 remaining issues with it that I can't solve:

1. It can't handle files that have % and other special characters in the name. This is the most important issue for me.
2. It prompts me twice for my credentials and MFA login. I'm fairly sure I know why (there are two calls to Connect-PnPOnline, one to our admin sharepoint url to lookup the onedrive url for the employee in question, then the connection to that onedrive url itself), but I don't know how to combine/reuse the authentication from the first on the second.

I was wondering if someone could help me fix these? The code is a little lengthy, so I've posted it to pastebin rather than directly to here.

https://pastebin.com/m05sqS9y