Your Natal Ficus is a hybrid and not as hardy as some of the more common Ficus species. Otherwise, it does not require any special conditions.
Getting bare-rooted cuttings established is always dicey during the transition. Most problems start with the roots and their pot and potting mix and moisture level. If you don't get that right, then light, humidity, etc won't matter very much.
Your cutting should be in the smallest pot possible to barely accommodate the roots and enough porous potting mix to barely cover them. The small pot will help minimize the possibility of keeping the soil too wet for tender new roots. The trick, then, is to keep that potting mix slightly damp.
Keep it in a warm sunny indoor location. Natural light is better than artificial. The variables are too great outdoors (temperature, wind, rain, etc.) so I recommend keeping it indoors at least until it is well established.
If the soil is kept properly damp, then humidity should not be a problem, although it never hurts.