Hi BladWor,
You could download and install the product using the ZXP package by following these instructions (https://forums.adobe.com/thread/1504330).
If it is not help, would you please collect log to us?
1. Create a file called exmancoreliblog.yes and copy it to
Mac: /Users/<name>/Library/Application Support/Adobe/Extension Manager CC/Log/
Windows: C:\Users\<name>\AppData\Roaming\Adobe\Extension Manager CC\Log
2. Restart Extension Manager and reproduce your issue
3. Send us ExManCoreLibrary.log file in that log folder to exman.beijing@gmail.com