This is the 8815th most frequent Japanese word.
果たさ
"果たさ" is the continuative form of "果たす," meaning "to accomplish" or "to fulfill."
In this sentence, "果たした" is the past tense of "果たす," meaning "to fulfill" or "to carry out." It refers to completing a duty or promise.
彼は約束を果たした。
He fulfilled his promise.
Here, "果たさ" is used as a truncated form before "なければならない," expressing the necessity to fulfill the stated goal.
目標を果たさなければならない。
We must accomplish the goal.
The term "果たさせた" in this sentence is the causative form, indicating an action that leads to causing something to be fulfilled or accomplished.