it's not easy to answer this question, as your stack might be anywhere from simple to super complex.
Assuming it's simple, you should create at least a firewall rule in your SG to allow either everyone (not recommended) or your IP/a CIDR (a subset of IPs) to reach the vm.
DSS will be answering at port 80 and 443.
Open your AWS portal, move to the EC2 service, find the vm you installed. Click on it, in the bottom section fo the screen you can see Security. Move to inbound rules, add a rule.
Here you should select HTTP as protocol, your IP (there's a convenient button my ip) and a note, if you want. You can then add another, with HTTPS as protocol. However I recommend you to only add the HTTPS one, even if this will give you an issue in the browser when you connect to DSS (due to the self-signed certificate used, but still better than no SSL at all).
Rules apply as soon as you save. Try to connect again.
If this doesn't work I'm afraid you have a more complex stack. You should contact your cloud administrators for help.