Trying to create short code is giving me 403 error

I created a table in the existing database in cpanel. I want to show data from this newly created table in my website. To do this, I downloaded a plugin that can create php code snippet for me to be used as short code in elementor.

To use the plugin, I enter the code to convert into a shortcode and when I click on submit button in the plugin, it throws an entire page of 403 forbidden error.

I tried 2 things and they didn’t work:

1. Deleted .htaccess file and recreated it using permalink refresh
2. Checked permissions of all folders and it is as it should be.

The page I need help with: [log in to see the link]