I use this all the time in my Divi websites. Divi allows you to insert a single button with the in-built modules, but I regularly want to have at least two and sometimes three buttons side-by-side.
To do this, you need two things. First, the HTML code, which you need to paste into a text module (add or remove <a> sections for more or fewer buttons).
<a class="et_pb_button" title="Call to action 1" href="#">Call to action 1</a><a class="et_pb_button" title="Call to action 2" href="#">Call to action 1</a><a class="et_pb_button" title="Call to action 3" href="#">Call to action 3</a>
That should work out of the box, but you might want to play with a bit of custom CSS to add padding, change colours and so on. For example:
margin: 5px; /* space between buttons */
I often create CSS for different coloured buttons, for example:
background: #161516 !important;
border-color: #161516 !important;
color: #ffffff !important;
/* class="et_pb_button button-dark" */
Original inspiration: the wonderful Girl and Her Mac