Condensation fabric - did I mess up?

[(Inte Alltid)Glad Ammatör]

Setting up a 30m2 cabin from Lövånger. As an under-roof, they've sent a condensation membrane. How on earth do I install it?
After looking around online, I see that some say the membrane should lie on the rafters under the battens. I've already nailed the battens and was thinking of laying the membrane on top of them, directly under the metal roofing. Will that work or do I need to redo it and do it right?

 

[Ring]

Redo, do it right. I can imagine there will be a bit too many holes in the canvas otherwise, and the ceiling might rub against the canvas. I probably would have chosen to attach the canvas to existing rafters and battens up a bit more (if by ceiling rafters you mean bärläkten) with 2" rafters.

 

[byggare henke]

does it say kondensduk on it?
could be säkerhetsduk and it's used on the rafters

 

[(Inte Alltid)Glad Ammatör]

Redo, do it right. I can imagine that it would be a bit too much drilling in the canvas otherwise, and the ceiling might chafe the canvas. I would have chosen to attach the canvas to existing beams and add a bit more battening (if by roof beams you mean the purlins) with 2" beams.

Finally found the manufacturer's assembly instruction and it should be done as you say, the purlins over the canvas. Sigh, thought everything was going so damn well

But oh well, a really big carpenter's cabin it will be when it's finished!