Here's a script that I was able to use to get all the users from a deployment. It's not a supported script, just something I was able to apply to quickly get all the users.

1. Grab the script: https://gist.github.com/Chris-DNSFilter/7eb6418491271638ace87b61d054d67f
2. Go to the page, e.g. Deployment > Users OR MSP > Users
3. Open the browser’s developer tools (press F12 or Ctrl+Shift+I).
4. Go to the Console tab.
5. Paste the entire script into the console and press Enter.

The script will scrape the table and download it as a CSV file named table_data.csv.