Anyone know how to activate this quest?

The wiki tells me that these are the requirements:
Ch7-8, Quest 76 Clear, Wil Lv34

I have done all of these, but I haven't gotten the quest

Try seeing all possible events in Yuidora or in your workshop. Go grind somewhere and return to see if there is a new event to trigger the quest.

The only event left in Yuidora is the Chapter advancement, and there are no events in my workshop. I also have no other available quests. Right now I'm trying to see if clearing more of the Arena does anything.

In that case, in what chapter are you? If you are in chapter 7, advance to chapter 8, as the quest won't be available in chapter 9.

I am in Chapter 8, that's why I asked this question, since I knew I wouldn't be able to do it in Chapter 9.

The quest is to speak with Elizasleyn about peace, and to recruit her. You need to fight against the angels attacking the city first and then go to Mishanshel.