Patterns without seam allowance were the norm in Holland when I grew up and for me it's very easy to add my own seam allowance. I don't even think about it, however for many international customers 'adding your own seam allowance' needs a bit more explaining. So here we go.
There are 4 different edges that a Wollyonline pattern piece can have:
1) The pattern edge needs to be placed on the fold
2) The pattern edge is a hem, this is something you will need to know and recognize
3) The pattern edge has a dotted line
4) The pattern edge is a regular seam

For this explanation I created a faux pattern piece with all 4 options. When I pin the pattern piece down, I need to place edge no.1 on fold as indicated on the pattern piece.
And hooray, the first edge is done : ). Edge no. 2 is a hem so I need to cut 1,5cm hem allowance along that edge.
Et voilà edge no. 2 is cut at 1,5cm from the paper edge. (Yes, it looks crooked, it's not me, it's the paper that pulls up the fabric some... that is my excuse and I'm sticking to it!)

Now onto edge 3, this edge has a dotted line so the seam allowance is already included. I need to cut straight along the paper edge.
I use dotted lines when the seam allowance is not all that important, usually these are square pieces.

Pattern edge no. 4 is next, this is a regular seam and so I will need to cut 6mm allowance.
That's it, done, all edges are cut with the appropriate seam allowance.

This means that with most Wollyonline pattern pieces you will need to cut a fabric edge all around them, a fabric offset if you like. That is because edges with dotted lines are not all that common.

The 6mm seam allowance and 1,5cm hem allowance that I recommend in the pattern description are the industry standards and that is why I use these in my patterns but, this is a secret, I do not use those measurements at all myself... I'm quietly walking out the door...

The 6mm allowance for seams is not my buddy because it's some random place under my favorite sewing foot, oh no! I prefer to line my fabric up right along the outside of my foot and that is about 8mm, so that is what I cut.

Cheers & Happy Cutting,
Christel