The theme works with PHP 5.4+ but it is always recommended to use PHP 7+ to have a faster and more secure website.
PHP Memory Limit
WordPress Memory limit should be 128MB or greater (256 MB is recommended by WooCommerce) For further reading check https://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP.
PHP Maximum File Size, Post Size and Execution Time values
If you are getting errors/warnings during file uploads, demo imports,saving customizer or page builders; it is recommended to increase these values. Contact your web hosting provider if you don’t have a permission to change the PHP.ini file.