"I like their floor."
Translation:Lubię ich podłogę.
Lubie is pietro could be also possible. For example, is we live in the same building and I would like to live on the same floor
I put this: "Lubię ich podłoga". It marked it correctly even though I forgot to put it in the correct case.
There's no such version accepted, so it must have been accepted with a typo - which frankly, is a bit worrying - typo is one thing, typo that makes a wrong case is another one...
"piętro" is the basic word, "kondygnacja" is a pretty technical word. I can't imagine anyone saying "Mieszkam na siódmej kondygnacji" or something like that. Please don't try suggesting it, I guess it would sound super strange in any of our sentences ;)
Besides, it seems that "kondygnacja" translates to "storey/story" anyway.