You don't have permission to access /wp-content/uploads/wtfdivi/wp_footer.js on this server.
Here are possible methods for resolving this error:
Method 1: Allow Access to the wp_footer.js File
One way to solve it is to figure out what is blocking access to the wp_footer.js file.
This isn't actually an error in Divi Booster. When Divi Booster is installed on a basic Divi / WordPress installation, the file will not be blocked.
If for some reason you are unable to track down the cause of the blocked access, there is a way to bypass it from within Divi Booster. In the Divi Booster settings, you'll find the following option: