I just downloaded the app (on IPadOS 17.sth) a few hours today and have maybe four files. Still, when I‘m on my canvas, an error message pops up, telling me that the file can’t be saved, since a file with the same name already exists.
Which isn’t the case… I even renamed the file multiple times.
Try with different names, and see if something allows you to save it. When that’s done, investigate further into why you could use the name you wanted. It’s usually something stupid, but do get to save your work first before looking into it.
It’s however hard to tell what’s happening at your end since we don’t know anything about your file structure, or existing files in your vault and what not.