(Of course you can just click the link here.) You’ll be taken to a Microsoft support page that looks like this, at least the top of it does: Once that’s established, the robot will provide the following URL: Tell it you are trying to activate Office 2011 for the Mac.
You won’t be prompted to provide an Installation ID. You will be connected to an automatic system. UPDATE Monday, August 28th, 2023: There’s a new and better way to do this.