If your device displays "MAC not registered" and points you to this help page, you've purchased hardware from someone other than TRMNL.
You will need to purchase a BYOD license (Bring Your Own Device) to use usetrmnl.com as your server for your BYOD device. You are also welcome to run your own server (BYOS), no license required.
If this is your first device to connect to useTRMNL:
You can now claim your device using your order number and name. Then sign up for an account.
Once you have a usetrmnl.com account:
With a BYOD license you can easily add your MAC address yourself. Hover over your BYOD device in the top-right of usetrmnl.com and click on the gear icon, selecting the Developer Perks section. Enter your MAC address for your device and save.
Find more information here: https://docs.usetrmnl.com/go/diy/byod#build-from-scratch-advanced
If you have further questions about using usetrmnl.com for your third-party hardware, send us a Live Chat or email support@usetrmnl.com.