As a Principle:
Demanding profit on loan is Riba (Sood) and is Haram in Sharia. No amount should be charged as a profit on loan or credit given to another party. However, late payment surcharge and/or service charges may be charged from the client. Service charges are those charges which are not demand of profit on loan amount and its usage, rather they are other charges which are incurred because of other ancillary matters related to that credit arrangement or related to that service being provided in addition to loan e.g. for writing up of loan contract, for acting as an intermediary etc.
Also, it is consumption of interest which is Haram, the one who has to pay interest to others (due to any personal reason) can do so as Quran has not condemned the person who pays interest, (Please see: Discussion 72050)
Regarding this App. Oraan:
It is principally not a loan transaction, rather it is a pool of money contributed by people from where people get a share on their turn (closer to insurance premium) and in case a person wants to get a payout which is out of turn, then he/she has to pay an extra fee which is justifiable and can be categorized as Service Fee. There is no element of interest in this arrangement.