Unity IAP Import button not working

I’m following this tutorial to import unity IAP plugin.
https://unity3d.com/learn/tutorials/topics/analytics/integrating-unity-iap-your-game

When I click import the package is not downloaded to the project. I tried to close and reopen but not works at all.

Please suggest

What version of Unity are you using?
I get a similiar problem with the import button not working and I’m currently using version 5.3.5.

I click download and then import, but import doesn’t work. So I close down Unity and reopen, the import button now works on this asset. Repeat for every other asset you download.

Otherwise click on the asset title and click on this import button.

Finally figured it out myself that the proxy in my office is the culprit. I was able to browse through unity store and also services but not able to download.

Connected to home network and I was able to import IAP plugin with one click. So download doesn’t work if there is a proxy server.( Unity version 5.3.4f1)