The issue has been resolved and testing confirms agents are installing fine. We've fixed a minor caching issue on our API servers which was the cause.
Thank you for your patience.
We have received reports of users being unable to install USS agents and USS gateways across all regions. Upon attempting to install the user will likely see WinHTTP Error 12002 This has been escalated and is being resolved by our systems team.
Apologies for all the inconvenience.