At the moment, there is a small issue with some of the online services catering to downloading Blazor through the Telerik Control Panel. We are working on setting it right, and we will get back to you here once it is fixed.
In the meantime, you should still be able to download the package from our nuget feed. If not, you can download the zip archive from your account and use it locally. You do not need to install UI for Blazor in order to use the components.
Progress Telerik UI for Blazor