Yesterday I complained that some combination of factors had made it impossible for me to evaluate an expensive tool for my day job. The manufacturer responded overnight:
First, we want to express our apologies for experiencing login problem. This is really uncommon and is usually related to OS restrictions. We also want to thank you very much for your interest in Telerik products. We are sure you will be able to build beautiful applications with lots of rich functionality really easy with guaranteed support, demos and documentation, etc.
Back to the login problem. The trial installer is an application that provides web login flow. This means that when you click on Login, your default web browser will be launched landing on the login page. If your system is configured to block applications to launch the default browser, the flow will be interrupted. From the provided error, we can see that System.Diagnostics.Process.Start fails to launch the browser. This information, however, is insufficient to know what the exact reason for this failure is.
We did a quick research and found a solution for a similar problem - OpenWith.exe error. Could you please let us know if that resolves the problem on your side?
Well, then. That's helpful and articulate. They suggested a few options, one of which is simply to use their private NuGet feed, so I will try that first.