I get the Adobe login screen when I try to render

Adobe’s licensing allows you to have unlimited render machines as Render-Only nodes. This means you can use After Effects to render without being signed into Adobe Creative Cloud.

Render Boss can signal After Effects to open in this special mode. To do this, just check the option Render as Render-Only node found in Options -> Render

With this options checked, you should be able to use Render Boss in a machine while being signed out of Adobe, and without the Sign-In pop window showing up.

Do note, that if you open After Effects while Render Boss is rendering, it will open in this render-only mode where you can only use the Render Queue and nothing else.