Where can I get a Normal Map for my Garment?

Hello, I'm very new to using Substance Painter (and 3D design in general) and I have been following some tutorials online to help me get started. My aim is to learn how to create realstic looking garments for my work projects. Right now, I have managed to greate my first sweater in Marvelous Designer, and have exported over to Substance Painter. 

I am following the guide here: https://www.youtube.com/watch?v=yELNQnveIMw yet I'm confused where to get the 'Normal Map' from (video timestamp at 0:53)? Without the Normal Map, I'm not sure how to progress.

Please can you help me understand this?

Many thanks!