Taps might have meant something clear in a particular time or place, and I'd certainly "get" it if someone tapped rapidly and rhythmically on my floor or ceiling, but I do know from experience that it's hardly universal. I tried it with a downstairs neighbor friend once when I needed sleep and they kept practicing guitar. They asked me later what was up with the tapping, which just annoyed them and they didn't realize was deliberate.
I'm not betting on this neighbor being MORE understanding than my friends.
And now I'm singing, "Knock three times on the ceiling if you wanna dance. Twice on the floor ..."