Hey there and welcome to the Community, @Rupert_Pfaff 
You just need to add this text to the Button Text field on the Content tab, and you’ll get the same button:
If you want to redirect users to WhatsApp on bubble click instead of opening the chat window, you can find the solution in this guide - WhatsApp Chat: How to open WhatsApp app on bubble click instead of the chat window.
Let me know if it helped or if you have any questions left 