It's a challenge for the side quest that's going to start during Spring Equinox. We are asked to help the Alchemy Professor  - Aubrin Bluewing. The quest is not required to pass the semester, it's just a little extra for those who want it. Reward for taking part and completing it are going to be guild reputation points.
The side quest does not need to be completed in April, you can complete it anytime before Autumn Equinox starts (August) G decided to get rid of the time limit, so complete the quest anytime you want. I got rid of start and finish dates because you can't have a starting date and no ending date, but remember that this challenge began on April 1st 2023.
Okay, I thought I'd update the choices as I go, but since it's multiple choice and they lead to different places (and G requested that we do not peek ahead), I won't be updating prompts so please use linked quest folder to find out what your next prompt is.

Since there's such range of number of books that can fulfill the quest, first 4 prompts will be regular, next 8 will be bonus ones and the last one will be also regular. So no one is left with unfullfilled challenge but also so the last one is the final book.

Orilium is a readathon created by G, here's the initial announcement, here's an explanation of everything that happened until now, here's announcement of this round, here's announcement of the year long readathon, here's the link to G drive with all materials for the readathon).
Here's the link to the quest folder.