Versions 1.8.0 and higher have the option to add phone / whatsapp buttons.
This article will show you how to implement them. Simply go to the module, and to the section 'Tel/Whatsapp buttons', and enable the feature.
You can set a phone number and/or a whatsapp number. If blank, the button will not show.
When active, the buttons will appear at the bottom right of your page.
A whatsapp number should be a mobile number, like this:
the mobile number is 0624759211
then you should enter 31624759211
where 31 is your country code.