A Certificate Signing Request (CSR) contains information used when requesting a certificate from a certificate authority. It is created from a private key and includes information such as the requested domain name.
The CSR itself is not the installed certificate. After the certificate authority processes the request, it provides the certificate that must be installed with the private key used to create the CSR.
Keep track of which private key belongs to each CSR. A certificate issued from one CSR will not install correctly with an unrelated private key.