How to I make Ores not hit each other in Zonix's Simple Sandbox Tycoon Kit?

Use collision groups.

local PhysicsService = game:GetService("PhysicsService")

--Create the collision groups.
PhysicsService:CreateCollisionGroup("Players")
PhysicsService:CreateCollisionGroup("Ore")

--Add the BaseParts in every player's character to the collision group "Players".
game.Players.PlayerAdded:Connect(function(player)
    player.CharacterAdded:Connect(function(character)
        for i, part in pairs(character:GetDescendants()) do
            if part:IsA("BasePart") then
                PhysicsService:SetPartCollisionGroup(part,"Players")
            end
        end

    end)
end)

--Make players not collide with ores, and ores not collide with ores.
PhysicsService:CollisionGroupSetCollidable("Players","Ore",false)
PhysicsService:CollisionGroupSetCollidable("Ore","Ore",false)

and then use this when the ore is spawned:

--Add the ore to the collision group "Ore".
PhysicsService:SetPartCollisionGroup(Ore,"Ore")

where Ore (the variable, not the string) is the ore that spawned.

Here is an article that explains it: https://developer.roblox.com/en-us/articles/Collision-Filtering