The first thing to do is to install this free plugin from WordPress Plugin Repository: SVG Support
**We are using SVG images for our Pro ET Layouts. If you did not install the SVG plugin, then our SVG images will not be imported & you will see empty white space.

Now, after downloading the json file, you just need to:

Step 1: Add a new page at: WP Admin > Pages > Add New & edit it in Divi Builder.

Step 2: Import the .json file by following the steps shown in the screenshot below:

Step 3: Save it & done.

As for Theme Builder templates, you just need to go to WP Admin > Divi > Theme Builder to create the necessary templates & import it similar to the above screenshot.