Can I use acrylic craft paint on fabric?

Check out this tutorial:

Yes you can but it must be mixed with a fabric medium. https://blog.udemy.com/acrylic-paint-on-fabric/

Yes, you can use acrylic craft paint on fabric. However, if you want it to be permanent; you need to use 'fabric medium' in the paint. You can get it at the craft stores; you'll find it with the paints. Follow the directions on the medium bottle. Very easy! For best results, iron your project to 'set' the paint and medium; before washing. I always turn my things inside out before a wash; they last longer that way. Hope that helps, and Good luck!

I painted on my clothes long before there was a fabric paint or a fabric medium. I thinned the paint with water and used somewhat like a watercolor technique. If you apply thick the finished will be more stiff. I enjoyed doing it and still have some of the garments 30 years later. Eventually, a medium came on the market and you can add to the acrylic paints to keep them softer. There is still some stiffing but that is understandable. Using a dye to paint would be more soft but requires more steps. Put a plastic covered piece of cardboard inside the garment when painting so paints do not glue your garment front to back. When it is getting dry life the painted side and separate it from the cardboard but leave it in place to finish drying. Later I began to add glitter to the paint mixture and enjoyed a new experience. But was I smart enough to develop this into a business. Absolutely NOT.

I would try your technique on some scrap fabric and see how it works. Acrylics with the medium would not be thinned a lot so should be OK and still not be too stiff and will wash more easily. You could use a resist on the fabric under the stencil to keep the pain from moving under the stencil but that would be time consuming an another headache.

You can but you have to add medium to it

You can, but you will need to mix it with a fabric medium.