Error in activating the plugin!

Hi there,

I just joined the Full Membership package & started with the Appointments+.

However, as soon as I tried to activate it, I got the following message:

"Plugin could not be activated because it triggered a fatal error.

Fatal error: Uncaught exception 'Exception' with message 'Google PHP API Client requires the CURL PHP extension' in C:\wamp\www\wordpress\wp-content\plugins\appointments\includes\gcal\Google_Client.php on line 21

( ! ) Exception: Google PHP API Client requires the CURL PHP extension in C:\wamp\www\wordpress\wp-content\plugins\appointments\includes\gcal\Google_Client.php on line 21"

Right below this message, there is a table which is titled: "Call Stack" in which the Function is "nggLoader->exception_handler( )" and the Location is "..\nggallery.php:0".

Can you please guide me in what could be wrong & I cannot activate the plugin.

NB: I am using the Pagelines Framework theme; however, I tried with other themes, but with no results. I also tried deactivating the other plugins, but still no results...

I would greatly appreciate your prompt response.

Thank you in advance,
Andy