Taking care of snails is more than just feeding. First, housing must be in order for the snails to feel good. In addition, it is important to give them proper food. And of course, the humidity must be monitored, calcium must be available and often a water bowl for them to go in to.
My land snails are largely housed in glass terrariums with adequate ventilation, heating and light. In addition, I still have a number of concrete plywood terrariums, but these are yet to be replaced. In addition, I use plastic curver boxes to let offspring grow up or for new species. The advantage of this is that they are easier to clean.
The substrate consists of a mix of potting soil with reptibark (wood chips), cypress mulch, dried leaves of oak or beech and some calcium. The thickness of the bottom layer depends somewhat on the snail species. Large animals that like to burrow naturally need a thicker layer than small species. I often place plants in the terrarium, although this is not possible for every species. Some plants will also be eaten faster than others. The terrariums are for the snails and if the plants are nibbled on, that's bad luck. Some branches, some larger leaves and sepia complete the picture. A bowl with some water is handy, but it must be placed in such a way that it cannot be knocked over quickly, otherwise the terrarium will be soaked after a few days and no longer suitable for the snails.
The temperature is important. Some species should absolutely not be kept warm, others should. Cooling down at night is often necessary and is also natural. Also keep in mind that some species will not be active all year round.
If you have the opportunity, you can make your terrarium bio-active. That is, you add a clean-up crew, often these are isopods. I myself have tropical isopods everywhere that clean up the surplus of food and feces.
Nutrition is not always an easy matter. Some species eat absolutely everything, others are very picky. The most important things for my snails are zucchini, cucumber, lettuce, mushrooms and to a lesser extent carrot, pear, dandelion leaves, ... Some species also need a few branches to gnaw on or some dried leaves. It is often a matter of trying what is best for the snail species you have bought. And besides, they don't always like the same things with someone else.
Do not always give the same food, but also alternate. I also regularly give pond sticks and gammurus.