Importing .PEM key on Windows 7 on the command line

I am looking to import three PEM files, two certs plus a key, with this answer working to add the PEM certificates:

• The RSA key is generated by GCP for a MySQL instance and I receive this import error:

  CertUtil –AddStore -Enterprise –f "Root" C:\Certificates\client-key.pem
  
    CertUtil: -AddStore command FAILED: 0x80092009 (-2146885623 CRYPT_E_NO_MATCH)
    CertUtil:  Cannot find the requested object.