"He does not like you."
Translation:On ciebie nie lubi.
They mean the same. "Cię" is the not-accented form, it definitely shouldn't be at the beginning of a sentence, and theoretically not at the end (but it definitely is in short sentences like "Kocham cię", "Nie lubię cię" etc.). "Ciebie" as the accented form, takes our attention, often shows some contrast. "Ona kocha ciebie" = "She loves you (and not Tom)".
In this sentence both should work. "On cię nie lubi" sounds neutrally, just a statement. "On ciebie nie lubi", at least to me, shows a contrast, a 'correction' of my views - I thougt he likes me, but it turns out, he doesn't.
Hm. „Ciebie” - you (singular), was (you plural), Pani/Pana/Państwa - you (showing respect). This is rather unidirectional translation, because of grammatical cases. If you want to translate from english, then you must determine which case to use: you (singular) -> ty, ciebie, tobie ...
You are half-right. "Ciebie" is a pronoun, not a preposition, and Polish doesn't like short pronouns at the ends of sentences; however, Polish allows the long forms of pronouns at the ends of a sentences.
And, finally, "On nie lubi ciebie" is an accepted answer.