Does the editor require iceborne?
No it doesn't. I don't have it and it works fine.
What does that error indicate then? Wrong game version?
Unfortunately, I don't know.
If you are sure that you have the latest game version as well, you could try simply redownloading the trainer again to see if it was corrupted by any chance.
If that won't work eithe, please open a support ticket here: Link
Click on the red "Open Support Ticket" button and fill out the form.
Thank you,
Ben