諦めた is the ta-form of 諦める meaning “give up”. Ta-form of a verb followed by ら means “if”, “when”, or “after” depending on the context. So, 諦めたら means “when you give up”.
そこで means “at that point” in time. It’s used in response to the statement mentioned before or the situation that happened before.
試合 means “a game” or “a match”.
終了 means “an end”. It’s the same meaning as 終わり but 終了 is more technical and official than 終わり and 試合終了 is often used as a word meaning “the end of the match”.
だよ is combined with だ attached to a noun or na-adjective and the sentence ending particle よ used to make the listener aware of the information.