To "get credit for" usually refers to someone, or something, being recognized, praised, or awarded for something they did. Some examples:
"The best player usually gets credit for their team's victory" <- This expresses that the best player on the team usually is recognized and given praise whenever their team wins
"I didn't get credit for my answer on the test" <- This expresses that the person did not get awarded any points on the test for an answer they gave.