Is there a deposit?

A cleaning fee, if there is one, is set on the listing and shown under the price before you book — it isn't a surprise at the door. Same for an extra-guest charge.

A security deposit is different: that's the owner's own arrangement, agreed with the owner and not collected through the site. Ask about it before you confirm.

Ask in the message thread on your booking rather than by phone, so the answer is written down and timestamped where you can both find it.