The free Lifter LMS plugin lets you create and sell courses on your WordPress site. This post has a few thoughts on using Lifter LMS with the Divi Theme.
Divi Booster doesn't currently have any features targeting LifterLMS specifically. It used to be useful for enabling the Divi Builder on LifterLMS courses (as described below), but this functionality is now included in Divi itself. Divi Booster does, however, include plenty of options for customizing Divi which may be of general use on your Divi / LifterLMS site. You can see the full Divi Booster feature list here.
You can enable Divi Builder on Lifter LMS custom post types within the Divi, by going to "Divi > Theme Options > Builder > Post Type Integration > Enable Divi Builder on Post Types" and enabling each of the LifterLMS post types.
One option for integrating Divi and LifterLMS, which I haven't yet tested myself, is the free Lifti add-on for LifterLMS. It offers various features for improving the compatibility between Divi and LIfterLMS.
I'm always happy to try to solve problems people are having with Divi, including compatibility issues with plugins such as LifterLMS. If you have any questions about how to get something looking / working a certain way, please feel free to give me a shout.
Enabling the Divi Builder on Lifter LMS lessons
I've previously written about how you can enable the Divi Builder on custom post types. There are some requirements for this to work, namely that the custom post type supports the standard WordPress editor box, which fortunately applies in this case. So the method described in that post will work on Lifter LMS lesson pages.
My Divi Booster plugin includes an option to enable the Divi Builder on custom post types, including Lifter LMS lesson pages, without the need to mess around with code.
You will find the option in Divi Booster, under "Divi Builder > Standard Builder > Enable Divi Builder on Custom Post Types".
Enabling the Divi Builder on Lifter LMS courses
Unfortunately, the method described in that post won't work on Lifter LMS course pages. While I won't go overly deep into the details, it's due to the non-standard way in which they use the WordPress editor box.
Fortunately, it's possible to work around this. The following PHP code will make the necessary changes to enable to the Divi Builder to be used on Lifter LMS course pages:
I've updated Divi Booster's "Enable Divi Builder on Custom Post Types" option mentioned above, so that as of v2.3.5, it will include this code and make the Divi Builder available on Lifter LMS course pages.
The result (once you click the "Use The Divi Builder" button), will be that you can edit the course's "Enrolled Student Description" using the Divi Builder, like so: