Mac OS  (MacBook Pro, MacBook Air, iMac, Mac mini, etc.)

1. Dowlnoad the Zscaler Certificate HERE
2. Navigate to Finder > Applications > Utilities > Keychain Access
3. Select "System" in the left-hand column.
4. Open File > Import Items and import the downloaded certificate file into the "System" keychain.  Enter your password if prompted.
5. The certificate should now show a red X which means it is not trusted yet.  Double-Click the certificate, and under "Trust," changed the setting at the top (When using this certificate) to "Always Trust."

For more information Click Here to visit the Apple website.