It uses layers, so shift for example is F or J. You push and hold one or the other, then push the second letter that you want capitalized. It's weird and hurts my brain, but apparently it's really efficient if you suck it up and adapt.
it took me awhile to adapt myself, currently running a 36key fifi, also split ortho. took me awhile with colemak and layers, but man the payout is sweet. gradual but sweet.
i can't imagine going back to a regular staggered 60% board now. my old ap2 board seems cluncky and awkward now after adapting to the 36key fifi.
Layers. Think of Shift key as turning on the CAPS layer, and Ctrl turning on the cut/copy/paste/save/new layer. Add more combos a layer keys, and every key ends up having 3-5 combinations that can replicate an entire keyboard.
Instead of two thumbs covering only one giant key (space), you give each thumb 2-3 keys. And 1-2 of those are to shift layers, so it becomes pretty natural once you get over a learning curve.
It’s for efficiency and ergonomics. Your fingers never need to move further than one key away. Your pinkies will thank you for not having to use all those keys.