1. Are you activating the game on the right platform?
Often customers purchase a product on one platform and try to activate it on another (e.g. Steam key does not work on Netflix, etc). Please check again if you’re trying to activate your key in the designated platform.
It’s easy to make a mistake when rewriting the key. Please check if there are no swapped similar characters, e.g. o the letter and 0 the number, might help.