You are likely using an older version of PHP than the required version of 5.3. You can either contact your hosting provider to upgrade your PHP version or download and install a version prior to V7 of the basic/free plugin here: https://wordpress.org/plugins/wp-google-maps/advanced/ (at the bottom of the page)
The latest version of the Pro Add-on is version 8. Could I kindly ask if you could please confirm which email address you used to purchase the plugin so I can take a closer look to determine if you have access to the updates and send you the latest version if this is the case?
Thanks for your time and I am looking forward to your response an assisting you further.