Proget API keys support uploading and downloading upack files by including the header:
`'X-ApiKey':'<apikey>` in the http request instead of needing a username:password authorization.

If a global configuration API Key is configured, then the API Key can be used without a username/password authorization (not possible with SAML authentication in proget) in order to upload/download packages.

See https://github.com/josh08287/inedo-proget-plugin/tree/use_api_key_for_upload_download for a basic implementation that is possibly incomplete (without documentation updates). Note: I'm not a java developer so I just made a naive approach to do what I wanted.