Not sure which door you were using. The one I went through (the large double doors leading into the building) you just turn left and go up a set of stairs that lead you directly to the stage.
It's pretty easy to find if you explore the school, but I agree that the school itself is kinda mazelike has doesn't have enough landmarks inside.
I really think that the school content (classes and such) needs to be rushed. the game makes basically no sense without it, since it's a university setting but you never actually go to class.
Well, ignoring the fact that's it's an Adult game with barely any erotic content, what needs to be fixed, is the game's economy. A lot of times, you don't actually get the money your told, from completing an objective (the janitor job flat out broke for me after one attempt).
In order to advance one day, you basically need 2 sources of food and water, which means you have to spend somewhere between $24 and $64 a day. Except that most quests reward you with about $5 (and the photographer questline is long, but a finite amount of money). It's excessively difficult to save up for the more expensive quests (like buying all of Evie's clothes). Although, at the same time, the fancier stuff you buy is worthless; you can buy computer parts, but they're not really implemented, whereas the adult toys can't be manually used, and are rewarded/used for the end of the photography questline.
Based on the description of the game, there were plans for Ashley to be a Cashier, and when you talk to the grocery store clerk, she even mentions "Here's your check." That's not even mentioning a ton of other things they boast about the game, that aren't remotely ready.
Not sure what they've been working on, considering this game has been around quite a while. When I went on their Discord for help with where the "stage" was, one of their developers said they should probably add a better guide for that quest, but that they were more worried about whether or not to "put in lights for the Concert Hall", than doing anything else. I would have more sympathy for the development team, if they weren't banking literally $6,666 a month (last a checked, a couple days ago).
Maybe the $25 version has more content though. That's probably where all their focus is. I'm not paying for it though. This game definitely isn't worth that pricetag, yet.
