Direction of fan in grow tent

I recently purchased a Vivosun 4x2 grow tent kit and was wondering when setting up the fan should I have air coming from outside in our inside out? Currently I have it outside in, but i started thinking about it and did a Google search that seemed to verify that either way works. Just wanted some feedback from fellow growers.

You want the fan to exhaust the air in the tent if you only have one, if you leave a vent or two open intake will happen without a fan.

It attaches to the top of your tent above your light. Heat rises so the inline fan pulls heat from your light and tent. You leave a bottom flap open for negative pressure, your inline fan will pull cooler fresh air in from that open flap, that air will run through your plants canopy, up and out. Its best to have a oscillating fan on the tent floor, then a pole, clip fan or 2 halfway up or so. Early in growth they can help guide heat up, in later growth the oscillating has the plants base covered while the clip/pole fan sends a breeze through the upper canopy. Really the more air flow you can have the better. Not so much on seedlings you don't even want the fan blowing directly at them, however in veg pushing 60%rh or more air movement aids against mold and mildew, a breeze also strengthens stalk and branches.

So should the flap should just be kind of cracked open or completely off? I also have the inline fan outside of the tent on top of it, wasn't sure if that made a difference. I have a small fan on the floor of the tent on getting of the opening blowing up and plan on getting a clip fan or 2.

I not only use the fan to exhaust heat but also to filter the smell by putting a carbon filter on the intake side of the fan.

The flap should have velcro just open it all the way. I've never ran my inline outside of the tent idk.

A pic of the top of my tent.
The fan is on the left.