I'm sorry to be the bearer of bad news, but you bought a real "paperweight" of a device. What I mean by this is that I suspect you bought a device that is a already out of warranty at an "affordable" price, but it is now going to cost you more than that of a new device in the long run. Having a locked device with a PIN you don't know (with no current subscription) means you can't factory reset the device, or else you lose the OEM cars that were already saved. Although the device runs Android, you can't root it as Autel locked that down for any of the Developer Options. The device doesn't have any physical buttons to allow you to invoke the bootloader or "download" mode to do anything in ADB. Your only choice as far as I can see is to buy a subscription to allow you to ship this device to Autel to have them factory reset it, then you can set it up, and download all the cars you wanted.

I bought a secondhand MY908/MS908 that had an expired subscription (but no lock-screen password) for a decent price. I still had to end up buying the subscription in order to be able to download the OEM cars I wanted to actually work on (despite the seller saying that everything was up to date as of 2020).
You can attempt to root the device, but you can't even initiate the process with the screen being locked