As bailey mentioned, you need to make sure that they have a suitable soil.
That is not the only requirement. The plants seem to be in a smooth container which is not normally, good for such plants. Does it at least have drainage holes in its base? Smooth containers normally hold a lot of water, even if they contain suitable Cactus soil. Not only do they need soil that drains well but, they also need containers that do. The best kind are unglazed, clay pots. These allow the water to drain and therefore, prevent the soil and plant roots from becoming soggy.
A big threat to any Aloes or Cacti is soggy soil. That will cause them to rot and fungus to grow on them.
Another thing to consider is that you have many plants close together, in one container. They can become overcrowded and suffer because of that. It is best to put each plant in its own pot. I've had multiple Cacti together in pots, like that, in the past. They did not do well and started to die. The only way that I could save some of them was by moving those that had not already died, into pots of their own.