The Divi theme comes with a menu module lets you place menu links anywhere within your page layout. One thing it doesn't include in its many options is an option to display the site title / tagline. If you'd link to add the site title and / or tagline to your menu module, here's how to do it.
Note: See here if you want to add the site title or tagline to the default header.
Display the Title / Tagline via Divi Booster
Divi Booster adds options to allow to you do so.
You can enable the options in the menu module settings at:
Menu Settings > Content > Elements > Show Site Title
Menu Settings > Content > Elements > Show Site Tagline