With the FMS option enabled on the EFB, you can set the MSFS flight plans to automatically be imported into the FMS (and thus used by the LNAV autopilot mode and HSIs) by selecting the FP SYNC option on the INDEX PAGE 2 > MOD SETTINGS page of the FMS to ON. When set to ON, any changes you make to the flight plan will also been shown on the MSFS VFR map.

With the FMS option disabled on the EFB, the LNAV autopilot mode and HSIs (with the change-over switch set to RNAV) will always be synced with the MSFS flight planner.