I'm running into the same issue (403). I already followed the steps at the link. In my myapp/conf folder I have: httpd-app.conf, httpd-prefix.conf, httpdvhosts.conf.
<IfVersion < 2.3 >
Allow from all
<IfVersion >= 2.3>
Require all granted
Alias /myapp/ "C:/Bitnami/wampstack-7.1.26-0/apps/myapp/htdocs/"
Alias /myapp "C:/Bitnami/wampstack-7.1.26-0/apps/myapp/htdocs/"
Hope you can help! Thanks!