Links not clickable on mobile devices in WordPress

You actually have a problem with columns overlap.

All you need to do is to make these two columns to have the same classes:

<div class="wpb_column vc_column_container vc_col-sm-6 vc_col-lg-6 vc_col-md-6 vc_col-xs-12">

Though Andrey’s answer will do the trick it may lead to undesirable consequences like this:

Now all links are placed over your header and popups