First, make sure you've run npm i -g serverless and added your AWS credentials.
Deploying for the first time can take 10-20 minutes since it needs to create the ElasticSearch instance. If there is an error, you may get ROLLBACK_IN_PROGRESS the next time you try to deploy. Give it a few minutes and then try again.
The AWS Free Tier covers most of these services, but running an ElasticSearch instance on AWS can be expensive. Make sure to run serverless remove once you're done.