How would I connect rigid pvc to a flexible hose for a drain
I had a similar situation with my condensate drain. Original setup was around the walls to the laundry tub - low slope pipe (not PVC - some sort of lesser plastic) that really didn't work very well (probably worked better 60 years ago when it was originally installed). I replaced it with PVC in a more direct route, ending on top of the floor drain.
Why do you need flexible hose? If the pipes are essentially stable, get/cut (very easy with PVC) pipe and connectors so that you end with an output down into the floor drain. Flexible hose may be a bit easier initially but is more likely to get messed up - moved to the wrong location, pinched, etc.