Hi There - I'm kind of new to this (and trying to make a work at home solution work for me), so I'm sorry if this is a dumb question or has already been answered.

If I have a 1920x1080 monitor, and I want to split it into 4 1920x1080 screens, can I do that? Or do I need to have something capable of a higher resolution? When I'm doing the split now, it is creating 4 960 x 540 screens.

What GPU are you using. Some GPU's allow you to scale your resolution even further, but note this could cause unforeseen issues.

Based on my experience you would normally need a higher resolution.

You could do a split horizontally but that would give you
480x1080

If you're alright with that,
right click Display Fusion > Monitor Configuration > Splits & Padding > Preset Spits. In the drop down select 4x1. & Apply.