This is the 10037th most frequent Japanese word.
追い付か
"追い付か" is the stem form of the verb "追い付く," meaning "to catch up."
In this sentence, '追い付かなかった' means 'could not catch up.' It describes the inability to match someone's pace or progress.
彼は走るのが速すぎて追い付かなかった。
He ran too fast for me to catch up.
Here, '追い付いた' indicates 'caught up,' referring to reaching the same level or position as someone or something in a race or competition.
試合が終わる前に彼らは追い付いた。
They caught up before the game ended.
In this case, '追い付かなければならない' refers to the necessity to meet a certain point or level of progress that is behind or delayed.