First off, for anyone reading this thread in the future, custom Download Plug-Ins are not for the feint of heart. If you’re going to use custom Download Plug-Ins, you may expect to have to read some some source code and perform some troubleshooting. Custom Plug-Ins are not supported by the BigFix Support team, and they won’t be able to answer questions on how to write or use them.
That said, 'tis the season for giving, and in my spare time I’ve written a Download Plug-In that I think might be useful in this case; either as-is, or as a useful starting point toward writing your own. As this is not an official supported tool, I’m hosting it in my personal github at https://github.com/Jwalker107/BESTokenAuthDownloadPlugin
As with anything you find on GitHub, please do review & understand the code before you consider using it.
The repo contains a README.md that I hope is sufficient to explain how to build, install, configure, and use the plug-in. If you have suggestions for fixes or improvements either contact me here, or send me a Pull Request for your changes. This is still a spare-time project for me so please do have some patience if it takes me some time to incorporate changes, and if anyone wants to spend more time on it actively feel free to fork the project.
At this point the plug-in does allow for storing multiple tokens and selecting which token to use based on regular-expression matching URL patterns in the config.json file. I’ve tested on Windows with the fine-grained Personal Access Tokens from github.com that @sryn describes above. At this point I’ve not tested with Azure DevOps, or with compiling the Python script to run on RHEL root servers.
In any case, I hope this is helpful and welcome any feedback you can give.