Or just manually download and install the library.
Install using Instructions found here.
You’re getting this error
because you don’t have the library installed.
And you can’t install the library through the contributions manager because of what ever reason that is causing this error.
I would venture to say that this is a internet problem but you say that you tried practically everything to fix it, so I can’t help you there.
But if your web browser works, then you can install libraries manually, and you won’t get the import error.
You also won’t have to install multiple versions of the PDE. 