Application "carddemo" failed to create. No file found in path carddemo/artifacts/

It seems you're encountering an issue where AWS is unable to find the application file in your S3 bucket, despite you being able to see it there. This could be due to a few reasons:

1. Permissions: The IAM role or user that's trying to create the application might not have the necessary permissions to access the S3 bucket or the specific object. Ensure that the IAM identity has the required S3 permissions, particularly the "s3:GetObject" permission for the specific bucket and object.

2. File Path: Double-check the exact path of the file in your S3 bucket. Make sure there are no typos or extra spaces in the file path you're providing when creating the application.

3. Bucket Policy: Verify that there are no explicit "Deny" statements in the S3 bucket policy that could be preventing access to the file.

4. Encryption: If the S3 bucket is using server-side encryption with AWS KMS, ensure that the IAM identity also has permissions to use the KMS key.

5. Region: Which AWS region are you working in?

To resolve this, you could try the following:

1. Review and update the IAM permissions to ensure they include "s3:GetObject" for your specific bucket and object.

2. Double-check the file path and make sure it's exactly correct.

3. If possible, try copying the file to a new location in the bucket to rule out any issues with the current object.

4. Check the CloudTrail logs for more detailed error messages that might provide additional insight into why the file can't be accessed.

5. Double-check you're in the same region as your S3 bucket

If these steps don't resolve the issue, you may need to contact AWS support for further assistance, as there could be account-specific factors at play.
Sources
Resolve S3 Access Denied error in CloudFormation | AWS re:Post
S3 bucket: does not have access or doesn't exist | AWS re:Post