Re: Mysterious Island Quest
If you have started this quest then which task are you having a problem with.
If you haven't started this quest then probably hasn't become active yet because there are still quests that need to be done first. Main quests have to be done one at a time and in order. As you complete one then next one will become active.
Here re is a link to information on this quest. https://thegirlwhogames.blog/2014/02/17/the-sims-freeplay-the-mysterious-island-quest/