I can launch the Windows Horizon Client from a Windows PC.

On a Chromebook, I've reinstalling the Chrome Horizon Client (non-Android) many times, but it never works.  The browser always displays the error "can't open this page".

Also, my understanding is; if you can use the Android Horizon Client on a ChromeOS device, you'll get the same error until the Android application starts (which could include starting the Android layer).  So you have to just retry every few seconds until it finally works.

With that in mind, I've even tried launching the ChromeOS Horizon Client, and then clicked the link on the Portal and still get the same error.  It's like the Portal page is looking for something that isn't there.