Looks like the ants are farming honeydew, they did that bad to my persimmon tree and a couple Salvia plants but never my citrus. I’d say use water on a pressure setting to try and blast them off and then coat it in neem, but the ants will continue to colonize something with them in my experience two seasons in a row. It’s a battle that I just ended up sacrificing my Salvia plants for the persimmon trees safety
The white critters look something like mealy bugs. There also may be scale involved. You could blast some off with high pressure water. Then neem or horticultural oil repeatedly at about two week intervals until they are gone. An insecticide might also help.