You need to generate CSR (Certificate Signing Request) and private keys. CSR key is required to generate a certificate (.CER file) from the Apple developer site. The private key will be used while creating the mobile signing key for building the mobile app.
To generate the CSR and Private key, follow the steps mentioned below:
Now, the CSR and Private key will be downloaded. You can proceed to create the certificate using CSR and signing key using certificate and private key for building iOS app.