Oops, if you're gonna save money working in the coffee shop to buy the spider drone... it's gonna take a lifetime, lol... Don't save for the spider drone, I'm sure it'll rain money from somewhere else
The circle in the apartments with several images of the girls (round icon), only indicates who lives there, but not that you can visit them at that time. The icon that indicates that you can visit them, or that there is some interaction, is the image of only one girl and the icon is square with the yellow background.
In Alexia's apartment you can't go at the moment.
To visit Olivia you must first meet her in the coffee shop (this happens at the beginning of the game).
To visit Charlene, you just have to visit Olivia first and wait a few days.
To visit Katia, you first have to do several trainings with her in the park, on the weekends.
Check the quests of each girl in the information icon (note: the quests are not active yet for Gina and Jessy)
Here are guides and information:
https://f95zone.to/threads/big-citys-pleasures-v0-2-4-porcus.16290/#post-2794566