Check out her page on the wiki
I send you a screenshot and I tried everything and nothing happened<img src="https://img.itch.zone/aW1nLzEyODIzMTcxLmpwZw==/original/vdD2zf.jpg">
I'm also having a similar issue, Maria's at level 30 but her event won't trigger. I've completed every single event except for hers. All girls are at the current max level, including side characters.
I've tried going to my room and lobby in the evening but it did not work.
The game is great tho, really looking forward to completing Maria's quest.