When I click on the import button on the library manager tab nothing happens.
You may want to read this post first (https://forum.arduino.cc/index.php?topic=459306.0) and add any additional information you might have.
There is also a PDF attached to the bottom of the second post there with details about importing sketches and libraries.
May I suggest you download it and read it as it contains some important tips for your type of issue.
If that doesnt work for you or you find another work around please come and tell us back in this post.
I couldn't do it earlier either, but it's working now.