I’ve only spun up a few basic EC2 instances for testing. The only difference from DO that I remember is that you’ll need to change to admin_user: ubuntu.
Otherwise, I think the Trellis README and docs are your step by step explanation. Like DO, you’ll want to use the AWS UI to assign the instance your public SSH key, power up the instance, add its public IP to hosts, then run the server.yml and deploy.yml playbooks.
I’d suggest giving it a shot, searching the docs and discourse if you run into trouble. If you encounter issues you’re unable to resolve, create narrow/targeted discourse threads. Enjoy.