Common problems that users face while installation are
Sometime permission of directory is not set properly, so it make the problem. Make sure your plug-ins directory has 0755 permissions.
CURL is an open source library and install on servers. If you do not have CURL or haven't configured it properly, install it or contact your hosting company.
Found errors? Think you can improve this documentation? Simply click the Edit link at the top of the page, and then the icon on Github to make your changes.