It’s nice that you were able to take in these rabbits. I looked at the cage and see that it is elevated. I wonder if the rabbits are not used to heights, that their former cage or pen had an opening at or just above floor level? That, plus being in a new situation may make them not want to come out of the cage yet. They had a conversion chart for the cage size, which is 4’10” x 2’6″. It is usually recommended that a minimum cage size is 2′ x 4′ for one rabbit, and that it’s tall enough for the rabbit to stand up comfortably, so that might not be quite large enough for two, although at the moment it seems that they are taking up very little space inside. They might feel more comfortable in an x-pen, with a hidey box for them to go into. That way they would have more space and be at ground level. But you can consider that for the future.
It is very common for some rabbits to be cage protective. They do not like hands or other objects coming into their cage. That can be due to the fact that they consider the cage to be their property and they don’t want any outsiders coming in, or they may fear that hands are going to grab them. I know a person who has had rabbits for years and they are still cage protective. Either reason could make them charge or growl or nip at you.
Could you put a ramp against the cage door so that the rabbits could hop down with ease, instead of jumping down? Even though it’s probably not that high, it could look scary to them, making them not want to jump out.
It would be easier to clean their cage without them in it, but you don’t want to stress them. If you can put a ramp there, maybe you can entice them to come out with some food. Unless their fur looks very raggedy, or looks like they are shedding badly, you could hold off on the grooming for a little while longer, until they got more used to you and their new home. If they do need it, use a soft brush on them if they will let you. If you have a top opening carrier, you could try to groom them when they are inside.
I hope that they will settle in soon and want to come out of their cage and interact with you.