DynamoDB table creation failed using .ebextensions

I'm trying to create a DynamoDB table in a bare-bones node project using a config file in .ebextensions. The app launches successfully but the table never gets created. My project structure looks like this:

app/
  .ebextensions
    setup.config
  app.js

setup.config contains the following:

Resources:
  StartupSignupsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      KeySchema:
        HashKeyElement:
          AttributeName: "email"
          AttributeType: "S"
      ProvisionedThroughput:
        ReadCapacityUnits: 1
        WriteCapacityUnits: 1

I then run the following commands to make a new elasticbeanstalk application:

git init
eb init
git add *
git commit -m "Initial commit."
eb create

The application launches, but with errors:

ERROR: Creating security group named: sg-8c926717 failed Reason: Resource creation cancelled
ERROR: Stack named 'awseb-f-nrju2hums2-stack' aborted operation. Current state: 'CREATE_FAILED'  
Reason: The following resource(s) failed to create: [StartupSignupsTable, AWSEBLoadBalancerSecurityGroup].
INFO: Launched environment: test-dev. However, there were issues during launch. See event log for details.
ERROR: The operation timed out. The state of the environment is unknown.

Does anyone have any clue about what's preventing the table from being made? I'm using a modified EB IAM role with full DynamoDB privileges. Thanks a lot!