Just a guess:
a) for AOC commercial air transport, authorisation by the CAA of the state where the AOC is held (which may well involve liaison with the Bosnian-Herzegovinian CAA); and
b) for private ops, authorisation by the Bosnian-Herzegovinian CAA.
In both cases, authorisation of the PIC and for case a) authorisation of the AOC holder.
Sim training required? Possibly. The go-around looks a bit sporty. 5% on one engine might be tricky and therefore involve escape routes, for which sim training would be v useful.
Best advice would be to contact the airport and ask them what they want.