They can pick it up outside from the droppings of other birds. If your chicks go outside you may want to give them a feed medicated with Amprolium, which controls the coccidiosis while allowing the birds to build up a resistance. Some medicated chick feeds are sold with antibiotics in them. There is no need to waste money on these. They eat much more than chicks and can overdose and die.
Adequate storage is needed for the feed to keep it dry and keep rodents out.
The galvanized trashcan is ideal. Chickens like other birds need a supply of grit for digestion. It is small stones that the bird stores in its gizzard, where they act like teeth and are used to grind up food. For chicks, grit is only necessary if the chicks have access to grain or other foodstuffs. Chicks on mash or crumbles don't need it.