In a composting toilet using the urine is diverted to a different container and kept separate from the poop and compost.
You can however just choose to poop in the composting toilet and then pee in a separate bucket to keep the poop and the urine separate.
If you urinate in the poop in the composting toilet it won't compost correctly so the urine needs to be diverted away from the composting poop.
In a composting toilet you usually have sawdust that covers the poop to create air gaps for aerobic bacteria to break down the feces.