Question about Midea Porta Split

The appliance is a closed refrigerant system ("plug & play") and requires little maintenance. Refilling is not intended during normal operation. The manual only mentions that work on the refrigerant may only be carried out by specialised personnel. There is no information on intervals or costs, as refilling would only be necessary in the event of a defect/leak.

I suppose as often and as expensively as possible.