WhatsApp & Email link not working

HI Can some one please assist. I have used MIT to create an app of a digital business card with clickable links in order for client to be able to save it with icon (as app) to his phone. Everything works fine accept for the whatsApp link as well as the email link. I get the following error. The web page at whatsapp://send? phone=(theclientsnr)&text=(message) could not be loaded because:

I have used a webview block with the actual card url.

I am new to MIT so I might need a well explained answer. If there is coding available to use where and how should I add it to the app.

The webview will only allow http, https, and file url descriptors, the whatsapp descriptor will not work

What about email?. When I put my email link within a webpage, The email link is not able to function whlile clicking on it.

see also this thread for an answer