Craft 3 vs Apache directory structure
If the craftcms folder is more or less the out-of-the-box Craft 3 installation, you should be able to just point your Directory blocks and DocumentRoot at /var/www/html/craftcms/web!

Only the web folder is intended to be public—everything else should be hidden, above the web root—think of it as sandboxing access to just one folder of your application.