Customers will often receive the Cannot Export the Private Key error when trying to install their client digital certificate. This error is seen because the option to mark the private key as exportable was not enabled during the initial installation of the certificate. To solve this issue please follow the instructions to locate and install your certificate again.
Do you have a PFX File?
Follow the support article and select the option "Mark Key As Exportable".
Unable find your PFX File?
You may alternatively Reissue the Certificate with a New CSR/Private Key.