you can't save your sketches unless you create an account, what a joke

Cannot and will not recommend. You are here to learn how to model and/or want to make your meshes in 3D, while sketching them prior? Well, go look further!

I really mean it. Go and look further for polygonal model engines, because this one here ain't it!
They yeeted the very basic "add vertices" behind the paywall. You are NOT able to add and form your complex structures. First I thought, during the learning books, about how to move and how to get along with the controls, that adding new vertices onto your sketch lines was bugged, because the videos weren't loading at all after bugging (glitching video on loop for the last 1 second), but no, the application will NOT allow you to place them at all.

I was sketching a basic goose, same issue here, no additional points in between the existing points. You can still copy and extend the line, sure, but you cannot make it more complex if already existent.
Same goes for any kind of mesh. You are not able to add loop, edge or any cuts to it. You cannot add any vertices to it, you can only move existing ones.

This is definitely a waste of time. I rather stick to blender than messing around with this. This application shouldn't be available for free, as it offers no value at all!