Are you playing on Mac, by chance? It's possible that it's an issue with the game's permissions - your computer sees a .exe file from an unknown publisher and assumes it's dangerous, so it only has "read" permissions and not "write." (Because it is not allowed to write to your hard drive, it cannot create a new save file in its folder.)
Last time a Mac user had this issue with an MV game, the (admittedly a bit janky) fix ended up being:
1) If you try to change the games "Options," it should result in an "Unknown Error," which lists a file path. I think it points to the Resources folder? (It's been over a year, sorry.)
2) Go to the location indicated in the error and manually create a folder inside titled "Save"
3) Ctrl+click/Command+click, I think? (edit: sorry, Windows user here - I guess Mac has actually added a right mouse button since last time I used one) on the Save folder and edit its permissions (requires Administrator credentials) to allow *anyone* to read/write/edit.
If you're not on Mac and/or those steps don't work let me know, I feel bad enough as it is making you go through that much trouble for a rushed contest entry lol. As an aside, if you're a UNIX wizard you can probably just change the game's permissions via command line.
Okay, so this is interesting. There's a folder called AppTranslocation that has led to the files being in a read-only directory that even as admin, I apparently don't have the authority to change? I did change it in the game itself, but… it doesn't seem to matter?!
AHAHA, it's a new security feature. I had to strip out the quarantine. Let's see if that worked well enough.
THAT WAS SO COOL!
I kinda wish, given that it's just that 1 major battle, there was an easier way to change formation (the game didn't let me, but I did figure out how to heal between battles), and I wish I'd been able to level up my … everything. Next time, I guess I will only outfit the main battlegroup since there's no more money or supplies after that.
Yikes, I love all these new updates that insist that the physical owner of the computer does not have the right to administrate said computer lol. I'm glad you got it working though!
And yea... next time I power through a short project like this, I'll be sure to give the player more explicit opportunities to customize and resupply. I spent a large chunk of the planning stage trying to put a military spin on the standard Fantasy RPG classes, so I probably should have let you explore that more :P.