Just tested in 1.37.1. No error message but no page created either. Pity because this functionality is useful.
Topic on Extension talk:AutoCreatePage/Flow
Appearance
It is indeed no longer working starting with 1.35.x or even earlier. Indeed it will be great to get a working version again.
Reported at GitHub. Not sure if it will get any attention though.
There is also https://github.com/Universal-Omega/AutoCreatePage, the repo the extension's page currently links to.
Both forks appear to work for 1.37.x, at least they claim to.