However, you should know the potential problem practicing meditation when laying down, and why sitting up is commonly given as advice for most practitioners: sleepiness.
Part of meditation is maintaining focus. It can be hard to do that when you are sleepy or feeling drowsy. And for many people, laying down can be a thing that contributes to feeling sleepy or at least less alert.
Maybe allow yourself to experiment, though. You should be able to discern after a few tries if laying down impacts your practice of meditating negatively or not, and how serious an obstacle laying down genuinely is for you. You might even discover this changes for you over time.
I tried the deep sleep one yesterday and it was amazing
Typically, the two most recommended positions are seated in a chair with feet flat on the floor, back straight, and the hands resting in the lap, or sitting on the floor (on a cushion or pillow if available) with legs folded/crossed, back straight, and hands resting in the lap.
From my experience, the upright position tells the body to remain conscious through the meditation, while lying flat signals the body to become unconscious (fall asleep).
With that understanding, there is no wrong way to meditate, and there are other methods of meditating in different positions or while performing different actions (such as a walking meditation).
I hope you find this helpful. Keep up the great work!