To make anything sticky in Divi you can easily do it by adding the Sticky Menu or Anything on Scroll plugin by Mark Senff.
It can be applied to rows, a column or a specific module.
I add this straight from the WordPress plugin window, so no need for an upload.
Then head to the Basic Settings and add a few bits of information as in the pic below:
• CSS ID such as #sticky
• Space from top of page
• Switch off for mobile if relevant
Then head to the Adanced settings to add the Z index. so it floats on top of other elements underneath.
If you want it to STOP being sticky before a certain row add another CSS ID such as #stop in the Push up element field.
Here is a great tutorial on Creating Sticky Elements