what year did this take place?

The compact ebook says it was contemporary.

In yr nightmares

Hard to tell. I would say pre-cell phone era but then there's that girl with the e-reader.

A few years ago, I read or saw that the production wanted either the '80s or '90s (I cannot remember) period for the film; however, budgetary constraints ultimately shuddered that idea/vision.

With such a low budget, the production just blurred between contemporary and the older period (s) they originally wanted.

The first girl in the beginning of the movie was literally using a cell phone. I think they stylized sets and had them wearing retro clothes to make the characters almost hipsters.

IIRC, the director deliberately made the year ambiguous to increase the viewers' sense of unease. Notice cars and appliances were from a range of years. As said, it was an amorphous 80s-90s nonspecific period.