joining an ec2 instance to a customers network/domain

Hi! I built a web app on an EC2 windows instance & want to put it on my clients domain. Once the server is on the domain, the users only have to go to the server name in their browser & the app renders. I haven't worked with AWS networking & want to know if I should I use Resolver, Amazon Active Directory, or AD Connector? Preferably quick & easy. I only need to join one ec2 windows instance to my clients network. Thanks in advance!