We will follow below steps to create a certificate signing request on your Mac : 

  • Launch Keychain Access App.
  • Navigate to Keychain Access > Certificate Assistant > then, Request a Certificate From a Certificate Authority.
 
  • Enter email address, a name and then check "Saved to disk" option. Click on Continue.
 
  • Save the certificate signing request (CSR) with the given name, we will need it later to create the Website Push Certificate.