Learn APIs Get Customer

I am trying to use the POST in the next training step but I keep running into this error. I have tried deleting and recreating but still run into the issue. Any thoughts here?

https://www.postman.com/rdaignault/workspace/postman-galaxy-training-daignault/request/20098101-80f25ff1-73a7-4f46-bd2d-60f3b562758c