How to import testlink test cases to zephyr scale with a xml file

Hi,
I'm trying to import test cases from testlink using a xml file, following this step by step https://support.smartbear.com/zephyr-scale-server/docs/test-cases/import/from-testlink.html, but when I click on "Import from File", the wizard doesn't show a testlink option.
What can I do to import this xml file?