First, Thank you for your purchase.
The problem is caused by php server configuration problem.
To be exactly, you need to increase the php max execution time & memory limit value.
You can set these values on your end.
Please add next php code on your wp-config.php file.
define( 'WP_MEMORY_LIMIT', '36000M' );
Please add above php code in wp-config.php like screenshot.
This file is in your wordpress server. If you can't do this, please share your site URL and admin credential.
You can share it after enable private mode. https://prnt.sc/ubs5x8
If you have any other questions, please contact us again without hesitation.
Best Regards, C-Themes