Unable to Load App error on custom domain name

This is normally because the domain name in the "Domain Name" field of your whitelabel settings doesn't match the domain name in the URL.

You need to ensure that both of these two fields are the same. For example www.Mydomain.com and www.mydomain.com aren't the same so wouldn't work. You also need to ensure you have setup the correct subdomain, so if you have set your DNS on www.mydomain.com ensure that you enter www.mydomain.com inside Interactr's agency settings and don't just enter mydomain.com.