Advice

Will this filter work efficiently being it's near the bottom? Newbie..

It should depending on the brand

I'd set it on a milk crate horizontally. End to the wall. More flow less carpet fibers and dirt.

it will work but not ideal, get it up out of the way when you can.

Nice looks like your growing a pot of lettuce too lol My snow pea is crushing it as well lol ...

Over 60% hunidity the filter will start to degrade.
Hot air rises.
And air i take needs to be low
Put it at the top

Then u are cicrulating the room stopping mould by stopping stale areas.
Creating fresh air to enter at base and circle plants..
Extracting hot air at top
And avoiding moisture which seems to be heavy so sits lower areas near plants more as they sweat.