I wonder how long it takes to come from Nifeng Liu B1123-1126, Yousong Technology Building 11F,Donghuan First Road, 518000 Shenzhen?
In this case it probably is true that the scanner will be dispatched from the UK using the Royal Mail miss-sold 48hr parcel service, so more likely 3-4 days delivery.
The item probably is a genuine Autel, whoever they are. The problem will be if it is defective or otherwise doesn't work on your car. You'll find you have to post it back to China to get a refund. Where of course it will never arrive unless you send it via a traceable service at your expense. And the cost of that will make you conclude it's not worth returning.
I buy stuff all the time from ebay. But I try and make sure the listing explicitly states that there is a UK return address. I wouldn't touch it with a bargepole if there isn't.