Facing Issue while setting up the development environment is to create AppStream fleet and stack.

The error you're encountering suggests that you don't have the necessary permissions to access the AppStream 2.0 image in the eu-central-1 region. This is a common issue when setting up the development environment for the AWS Blu Age L3 workshop. To resolve this, there are a few steps you should take:

1. First, ensure that you have sent the Activation email before starting the workshop. This is a crucial step that grants you the required permissions. You can find instructions on how to send the Activation email in the workshop introduction materials.

2. If you have already sent the Activation email and are still experiencing this issue, it's possible that there's a delay in the permissions being applied or there might be a problem with your account setup.

3. In this case, the best course of action is to contact the L3 workshop support team directly. You should email them at aws-blu-age-l3-certification-workshop@amazon.com and describe the issue you're facing, including the error message you received.

4. While waiting for a response from the support team, you can double-check that you're using the correct AWS account associated with the workshop and that you're in the specified region (eu-central-1).

Remember, access to specific images like BluAge-L3-Workshop-Image is controlled and may require special permissions that are granted as part of the workshop process. The support team should be able to assist you in ensuring your account has the correct access rights to proceed with the workshop.
Sources
Can't find the image: BluAge-L3-Workshop-Image | AWS re:Post

It looks like your IAM user is missing the appropriate permissions. Speak with your AWS administrator and ensure you have the correct policy and access applied to your account.