I was able to download the files from the browser but not through Unraid, then when trying it from the command line, as you suggested, I saw where the error occurred, it was refusing the certificate from my self signed Untangle UTM appliance. Once I added the github to the exception of not to be scanned by SSL Inspector, the plugin installed quickly and correctly.
All the other plugins that I have update automatically without problem, that is why I did not think about the Untangle appliance.
Thanks for pointing me in the right direction and the help.