Can I replace rolled oats with instant oats in a cookie recipe?
(Disregard previous version:  I did not notice this recipe had no wheat flour.)

This recipe gets all of its structure from oats.

Instant oats are pre-hydrolized, so that they cook faster.  Regular oats are just the natural oat, perhaps cut, and rolled flat.  They need more moisture and time to hydrolize.

The recipe will probably work, perhaps with a slightly different texture.  They may bake faster due to the fact that the oats are already hydrolyzed.

If you choose recipe where the structure comes from wheat flour, the type of oats will matter less.