Couldn’t activate because of “fatal error”

I couldn’t activate this plugin because of a fatal error wordpress is warning me about:

Fatal error: Uncaught Exception: DateTimeZone::__construct(): Unknown or bad timezone () in /home/nedb/public_html/camrent/wp-content/plugins/simple-schedule-notice/simple-schedule-notice.php:47 Stack trace: #0 /home/nedb/public_html/camrent/wp-content/plugins/simple-schedule-notice/simple-schedule-notice.php(47): DateTimeZone->__construct(”) #1 /home/nedb/public_html/camrent/wp-content/plugins/simple-schedule-notice/simple-schedule-notice.php(934): Simple_Schedulenotice_Class->__construct() #2 /home/nedb/public_html/camrent/wp-admin/includes/plugin.php(1909): include(‘/home/nedb/publ…’) #3 /home/nedb/public_html/camrent/wp-admin/plugins.php(172): plugin_sandbox_scrape(‘simple-schedule…’) #4 {main} thrown in /home/nedb/public_html/camrent/wp-content/plugins/simple-schedule-notice/simple-schedule-notice.php on line 47

I have no idea how to understand this. I tried to find that line 47 in the simple-schedule-notice.php file, it says:

$this->wp_timezone = new DateTimeZone( get_option( ‘timezone_string’ ) ); //wordpress timezone

No idea what the error is and how to fix it. Pls help! I really do like to activate this plugin, it looks legit something I can use for my site asap THANK YOU!