That fig tree is large. What's the diameter of the trunk at the bottom? Maybe about 2-3 inches (5-8 cm)? Hard to say from the photo. Maybe more. If they had that tree in a 5 litre pot (about 2.5 gallons), then it must be completely root bound. They must have been drip watering it or it never would have gotten that big with the roots restricted that much. I bet the root system can't really support that top under normal conditions. It attained that size under nursery conditions (lots of watering, maybe in a greenhouse with extra humidity, etc.
So even if you put it in a decent sized pot now, that doesn't change the root system that it has.
What really needs to happen is to prune the roots so that they are able to expand properly without being so bound up. However, if you do that now, it will most certainly drop all its leaves. They will come back, but no fruit this year. So you have two choices:
1. Take it out of the pot, slice off all the circling roots. Put back into that pot. All leaves/figs will drop, but by the end of this season it should have recovered nicely.
2. Leave it as is, water it regularly (at least once per day, and make sure it soaks all the way through). You may be able to salvage that one breba fig (woo hoo!). It may even keep its leaves if it can recover from the transplant shock. May even produce a couple figs this year. However, sometime early next spring, before it puts out leaves, you will want to take it out of the pot, and do as I mention in #1.