In CloudFlare Create Origin Cert
Copy pem file to Windows Server directory (ie star.mydomain.2026.pem)
Copy key file to Windows Server directory (ie star.mydomain.2026.key)
Issue command in Powershell: certutil -mergepfx star.mydomain.2026.pem star.mydomain.2026.pfx
Or if you have openssl installed: openssl pkcs12 -export -in star.mydomain.2026.pem -inkey star.mydomain.2026.key -out star.mydomain.2026.pfx
It will automatically take the pem file and the key file to create a pfx file. It will ask for a password.
Type in a new password.
Import into certificate store in Windows as normal.