Import the Client Certificate to the Client PC

Export client certificate from the pfSense router and download it to the client PC
Navigate to System > Cert Manager, Certificates tab in the pfSense webGUI
Click by the certificate to download a .p12 file containing the client certificate and key
Locate the downloaded file on the client PC (e.g. client1.p12)
Double click client certificate .p12
Select Current User
Click Next
Click Yes at the UAC prompt if it appears
Confirm the proper file is selected
Click Next
Click Next
Click Next
Click Finish
Click OK