Why did nobody tells this in fusion tutorials

I have been editing a video in DaVinci resolve and it kept crashing repeatedly. Sometimes it would fail renders, stop midway, etc. One thing that i knew was that this is not systems fault(I have Mac mini m4 24GB, that thing doesn't crash).

So i went scouring Reddit and YouTube to find what the problem was, but just couldn't find it. And just now on YouTube I was looking a simple tutorial on fusion and that dude also had the same thing going on.

And the thing he did: a simple 3 click process. Playback>render cache>user. And let the fusion process complete for a while.