Import the .zwo files as custom cycling workouts. Official instructions:
https://support.zwift.com/it/custom-workouts-ryGOTVEPs

Use your normal current FTP for the easy/moderate warm-up only; adjust intensity if needed. The test uses a free-ride block with no prescribed watts. Check trainer resistance and gearing before testing. Do not skip blocks or pause during the timed test. Save the full activity and select exactly the test interval for its mean power, including zeros. These files are for cycling, not running.

XML durations checked; loading and trainer behavior have not been verified in the Zwift app.
