Hello Isabella,
Welcome to Microsoft Community.
We noticed that you posted this thread in the Surface Go section, but in your description of the device model, you refer to it as the Surface Laptop Go first, so may I assume that the device model you're using is the Surface Laptop Go Generation 1?
If you are looking for a completely correct answer here, then I can inform you that Surface Laptop Go does not support Pen input. The device is working as expected.
So if the seller "promises" that the stylus you're using can write in the Surface Laptop Go, I wonder if there's a commercial scam involved.
Best Regards,
Mitchell | Microsoft Community Support Specialist