I downloaded the following design, Cute Embroidery christmas1968922. This is definitely not FSL. I put it on felt but wondered if it should have had a couple of layers. Any suggestions for sewout?

No, it isn't FSL. It looks like it is an in the hoop project. It should stitch out fine on one layer of good quality felt and using 2 layers of Solvy or wss Vilene.It only has 6,800 stitches.

This is her link

I don't know how to find that without a link to the page. Do you have a link?

I think I would use organza, but I am still a beginner. I am sure someone else is going to answer pretty soon.