Ok, so the reason you’re getting the error is you changed the settings on the last command. See how they all have words (Cut/Engrave), but that last one has numbers? That’s how you know you’ve changed the settings.
Click on it and click the back button and then select the Cut command again and it’ll revert to the default settings.
They may not have the 3mm draftboard in stock right now - they’ve been having supply issues because of the pandemic. That being said as long as it says Thick Draftboard at the top, and all the settings have words, it should print. Your custom setting is pretty close to the default one (I have a Basic not a Pro so I can’t confirm), so there must be a different issue.
Watch the laser when it’s trying to cut or engrave - you should see a pink light zipping back and forth through the tube (you might need to turn off your room lights to see it). If that’s not there it’s possible there’s an issue with your tube, but hopefully not because that would require it being shipped back for repair