404 Nginx Error with AWS Meta Capi

Hi,

I set up the Facebook/ Meta Conversion API with deploying it to AWS. I followed all the steps of deploying it and the stack was sucessfully created. The deployment url Also the dns was setup sucessfully. If I want to enter the Capi Dashboard, it can't reach the server and if I use the the ConversionsApiGatewayInstanceURL in the CloudFormation Output it gives me a 404 Not found Nginx Error.

I also can't connect to the ec2 Instance because it tells me that I use the wrong credentials (I use the user that I found in the Userdata). Session Manager ist not setup, ssh client connection timed out, EC2 Instance Connect gives me a "failed to connect to your instance" and Ec2 serial console doesn't work with my credentials.

What is the problem and / or how can I have access to my EC2 Instance so I can debug the Nginx Error? Sadly I am not so familiar with AWS products.

Kind regards and thank you!