Regular old flour works -bread or all-purose or even cake- but the dough had best be proofed away from too much moisture, ie no steam. Use an overly generous amount sifted onto the basket and with each success reduce a bit til you find a happy place.
Even spongy rye masses have come out in one piece with a jiggle-jiggle here and a hop hop tip. Think of that as walking the dough out instead of inverting.
Bits may stick but only minor flesh-wounds. Let basket dry and scrape clean.
If the problem is related to brand-new basket, may need to search for some 'seasoning' tips first.
The bakers couche is not just floured fabric, it is usually a hard wearing canvas
It is used to allow the dough to breath, and hold it's shape while your actual bread moulds are being used in the oven. The all over air gap allow the crust to dry slightly. A dry crust makes it easier to handle and bakes slightly more crispy
The flour is there to stop the soft dough from sticking to the canvas, but a with careful handling and a well worn in couche this should not happen
If you keep the couche dry it should not develop mold or mildew. Even if it does, leave it out in the sunshine, so that the UV light can deal to it. I can't imagine that the occasional normal household mold is going to form dangerous toxins that can survive the oven!
After use, give the couche a good brush down with a clean fine bristled brush, and store somewhere dry
If you have plenty of the fine perforated steel moulds, you wont need to use a couche, just use the pans
Best Answer
Seeing the recipe now, my only advice is: don't.
Long proofing is something which is done with white wheat bread to add some aroma. And it depends on the yeast having very good growing conditions.
What you have here is a quite complicated dough. It has a ton of pumpkin in it, and most of the flour is whole wheat. And then you are adding spices, which have yeast retardant properties of their own. This is a dough which will have trouble rising. Keeping it alive for 24 hours won't be too easy, getting a decent rise out of it will be worse, and getting good added taste instead of some off tastes with this mixture is in the stars.
And even if you managed to proof the dough well in a long process, you won't get the effect you are hoping for. In pure wheat, a long fermentation gives you subtle fermentation aromas, but nowhere as strong as sourdough, and a very specific texture which people tend to seek out. You can forget the texture in this overloaded dough, and the spices will cover the taste change pretty much.
Just use the recipe as intended, and if you want long-fermented bread, take a recipe which is meant for that, there are enough of those around.