Can we say "I want to meet the doctor who sits on the first floor or ground floor?"
Please check.
Thank you for making the relevant corrections to post #3.
Piscean's response in post #2 made a very particular point - that you said the doctor "
sits on the first/ground floor". That is not natural. I assume you mean that his/her office or his examination room is on the first floor. Also, we don't "meet" a doctor if we are looking for an appointment with him/her.
"I want to see the doctor whose office is on the first/ground floor."
Of course, if there is more than one doctor based on the first/ground floor, you're going to have to be more specific to whoever you're talking to.