lobby on context

[Unregistered]

depend on the context
can you explain how context can change the meaning?
what is the difference?

Let's meet at the lobby
Let's meet in the lobby
Let's meet on the lobby floor

thank you

[Anglika]

"at the lobby" - come to the lobby doors
"in the lobby" - come into the lobby
"on the lobby floor" - there are many different floors in the building; we will meet on the floor which is the lobby floor.