This document will guide you through exporting your personal certificate on Windows and Mac.
Open the Windows menu and type certmgr.msc in the search bar, select certmgr.msc from the search results.
Navigate to the Personal certificates tab.
Right click the certificate you want to export and choose export.
The Certificate Export Wizard will now open. Click on Next.
Click on "Yes, export the private key" then click Next.
Put a check mark next to "Include all certificates in certificate path, if possible" then click on Next.
Choose a password, which you will need to know when you import the cert, click on Next.
Give your exported cert a name and click "browse".
Choose a location to save the file, make it somewhere safe that will not be deleted, remember the location so that you can find it when you import the cert. Click next.
Click on Finish.
Open the Applications folder and choose Utilities > Keychain Access.
On the left side of the screen, select login as the Keychain and select My Certificates as the Category.
Highlight the certificate to export and open File > Export Items.
Choose an appropriate file name (mycert.p12) and directory, then press the Save button.
Set an appropriate password for the digital certificate and finally press the OK button.