Maybe a dumb question, but can Rampart not have 3 turrets out at once?

I’m pretty new to this game, and I was trying Rampart in the practice range to see if I should get her, and Sheila’s description would imply that she can have 3 turrets out at once, but whenever I try to place one when another already exists, it just destroys the first one https://tutuapp.uno/