Please tell me about AWS IoT

I am trying to connect to AWS using the sample AWS IoT on nRF9160-DK.

The certificate used for connection is a certificate issued by AWS. "E: aws_iot_connect, error: -119" is displayed and I cannot connect.
The certificate issued by AWS is set in the following file.

①ca-cert.pem: Root CA certificate

②client-cert.pem:Device certificate

③private-key.pem: Private key file

However, I am not sure if I have configured it correctly. How should I list the certificate contents in each file?