Did you choose Allow OEM Unlocking in the phone settings ? The comments in that article show more users with problems. With some phones (Motorola ?) you need to request a code from the phone company before being able to unlock.
Disclaimer : I searched for more information, and having used custom roms on phones before. I do not know anything about this phone brand.
Sorry guys, I thought I had enabled everything I needed to, but it turns out I forgot about the oem after all. If you're interested, here's what I'm getting now: https://imgbox.com/FRabXlF4
You made progress! Maybe you will need to wait for some days before unlocking works. And the company of your phone seemed to have a community forum, which is maybe useful ?