Welcome!

I think it's normal not ro remember every detail. The important part is to write down everything you rmember, because when you that, you are thinking about your dream and that is what helps with boosting your memory and recall.

Casette player is fine, since you also thinking about your dream when recording it. But I personally prefer paper or word processor to record my dream, so I can flip through pages, notice patterns, make notes about what worked and what didn't, and basically have it in front of me at a glance.