When we grow epiphytes in moss, its usually just sphagnum moss, and its usually epiphytes that can live long term in moss, like aroids. Although many hoyas can be mounted and also grown in moss. It looks like you have chosen a more decorative moss.
This is what an epiphyte in moss would typically look like. This happens to be an epipremnum Shangri la
Many hoya do lend themselves to growing epiphytically because, like a lot (but not ALL) aroids, they make adventitious roots to climb. Hoya do this as well. But the leaf morphology of this particular hoya, the rope hoya, doesn't lend itself to growing flat on a surface and hanging on by the roots. In order to get this to grow mounted or in a moss basket, you would probably need to strip the stems of leaves for a few inches, and mount that to a plaque, preferably cork or tree fern, under a pad of moss like you would an orchid or a dischidia. Then let the plant establish, and hang freely.
The best way to grow these compactas is potted, like Lin said, in a porous airy soil mix that you can douse with water, and it will drain quickly and freely.
Ground coconut husk can be a COMPONENT of such a mix, but is a poor choice to be the ONLY component because it tends to compact, absorb large quantities of water and stay wet, and grow mold like yours did. Chopped coconut husk is a better option that ground coconut husk.
