Not able to create code pipeline

Is your AWS Account recently created, as for newly created accounts it takes time until account gets completely validated. I'd suggest you to wait until the account is validated and configured with the standard concurrent builds limit.

Please refer this Workshop, where at the end same problem is discussed with it's possible cause.

If this doesn't apply to you then I'd suggest you to check number of concurrent running builds in AWS CodeBuild quota at service quota console for codebuild service.

If you see that quota value lesser than what is required for your account:

1. Select that quota and and click "Request quota increase" button at tope right of the page.
2. Enter new value under "change quota value" field
3. Clicke Request

Best way to get the clear direction is to reach out to AWS support to get it fixed as AWS support is well equipped to look up your account and pin point the problem but unfortunately with the basic support plan, you'd not be able to contact to AWS Support.

When you check the service quotas, make sure that region is same in which you are running codebuild.

Hope you find this information helpful.

Comment here if you have additional questions, happy to help.

Abhishek