Hi,
Sorry for the issues you are having I can help troubleshoot this with you.
When you look in the Plugins Directory do you see a folder titled:
events-calendar-pro
And what is the folder called when you mention this “I can see the version 3.9 folder”
If you have two different folders for two version of Pro that maybe the issue. You should have Pro only be in this folder:
events-calendar-pro
I’ve even tried to search installed plugins; no luck. I have no Add New option.
This feature will not work to find Pro as you can only get it through our site and is not a WordPress.Org Plugin.
Let me know and we can go from there.
Thanks