After unlocking the mansion, I was unable to beat the game because I do not have the necessary resources. The new tile everyday did not give me wood and I eventually lost after the rank got too high.
Good game though.
Exact same thing happened to me. Unlocked mansion at 20 but was 1 wood shy of building it, and I didn't get a source of wood from either free tile or collection gift until I failed to pay rent on day 40. The game has the potential to be great, only needing a consistent source of building materials. They need to be farmable or purchasable any time.