WP Mail plugin not sending the mail

Some issues is because php version of your server hosting not valid with your website.
First, you must check what php version that your hosting used, check from WHM->server information (right menu).

Now, back to your cpanel dashboard, seleck multiPHP manager, choose your site and select php version(right menu dropdown), choose with the same php version of your server hosting.

Back to your WP dashboard, WP mail SMTP and test send email again.