Need to add Tls1.2 to declaration setup file

[bstin]

Not sure if this is because of a change to github requiring TLS1.2 now?

Regardless, you need to specify:

[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12

As first line in the script in order to actually download the file with WebClient.DownloadFile