Max items means how many items a container will hold. So if it's set to 5 items and the container has 5 items, it won't respawn loot until it has 4 or less. (Some mods seem to ignore this setting, as well as some custom maps) Also remember some modded maps won't respawn. The current mod maps I know of that will respawn are South Muldraugh, Bedford Falls and New Denver
You need to set this on the Server.Ini file. The time frame doesn't matter, just make sure it's set to 2 or higher to allow for respawn
LootRespawn = 2, (1 is none, 2 is every day, 3 is every week, 4 is every month, 5 is every two months)
And on the Sandboxvars file
HoursForLootRespawn=2 (How many hours real-time for loot to respawn)
Set your time. It used to be IRL hours. But according to the devs it changed back to Game Hours
And loot apparently is randomized, so not all containers may refresh.
Here is a good starter explanation of the server files.
And where in Korea are you. I've spent some time there.