How to set the deposit and what is it purpose?

A deposit of 75€ is required as a guarantee via pre-autorization on the credit card prior to arrival. This deposit shall be fully refunded upon check-out, unless minibar consumption, defects are found in the apartment, its furniture or equipment, or situations of extreme filth or rubbish. The cost for re-establishing the condition of the apartment upon check-in shall be discounted from the deposit.