Whatsapp chat

Hi,
On my site https://difar.it/en/ at the bottom of the page (before the footer) there is a “Contact us here” button. I would like to make it so that when I click it the WhatsApp chat opens via your plugin. it’s possible to do it? I don’t want the little icon at the bottom right to appear but for the chat to appear just by clicking on that button. How can I do?

The page I need help with: [log in to see the link]