Hi, Thanks a lot for posting your query here. I am Jins here to assist you.Please do the following steps.
Log in to the Mac with a local administrator account (card NOT in the reader)
Launch Keychain Access form the Applications/Utilities folder
Insert the card into the card reader
In the Keychains panel of Keychain Access, select the card's keychain.
The certificates on the card will appear
In the right pane, click the first certificate
If 'This certificate was signed by an unknown authority' displays in red, double click it the certificate.
The Certificate Information window will open
Scroll down to the Extension section labeled 'Certificate Authority Information Access' and click the
link just below it (Ex. http://crl.xxxx.mil/getsign?DOD%CA99).
The CA certificate will download to the Mac
Close the Certificate Information window-
Quit Keychain Access.
Locate the certificate in your downloads folder and double click it.
The Add Certificates window will appear asking if you want to add the certificate to the keychain
Set the Keychain field to System and click OK.
Enter administrator credentials if prompted.
If prompted, choose "Always Trust".
The new certificate should appear under System in the Keychain Access window
Do the same process for each of the remaining certificates
Please remember these things when we deal with your issue. It may take more than one step/answer to solve a problem. So If my answers don’t work or if you are not satisfied, please don’t Rate my answer as Bad or Poor Service, but please Reply back to me by clicking the “Continue Conversation” or “Reply” button and I will gladly continue to help. Remember, only Rate answer after you are 100% Satisfied. Please do not rate an answer, if you are not satisfied.