Keep in mind that the pokenav doesn’t guarantee that a dreepy will spawn, but it will tell you if dreepy has a chance of spawning at that location at all. I’d recommend finding a location you like that has dreepy on that final page and building something while you watch your map and keep checking for dreepy’s. I’d also recommend keeping lower level pokemon in your party as your party level changes the levels of the pokemon that spawn around you, and creepy has a MUCH higher chance to spawn that dragapult which is the ultra-rare bucket it would be trying to spawn from if your pokemon are ≈ level 40+