your web server is configured with PHP settings that are too low for a theme with several plugins. Specifically max_execution_time and memory_limit. Thus, the web server is rejecting to save the theme options. This is not a theme fault or bug.
You can get your web hosting company to increase your PHP limits.
Recommended PHP configuration limits are as follows:
The theme and plugins require PHP version 7.0 or higher. Now is the time to think about upgrading to PHP 7.0 if you haven’t already. Not only because you want to be running on supported software, but you are guaranteed performance benefits! If your current WordPress host doesn’t support PHP 7.0 yet, we strongly encourage you to seek out new hosting.