For me, it is automatic :
1. create flightplan in SB and generate OFP data
2. load sim, FSL A320 in Cold n' Dark state
3. turn on battery, start APU, then turn in MCDU
4. in the AOC menu use INIT, send INIT request and FP is loaded into MCDU
5. in ActiveSky I can see route without LOAD or any other operation