A Spektrum is just a fancy JR.

Flaps is channel 6.

Did you go into the main programming menu on start up and activate your flaps switch? You gotta press and hold both left side buttons and then turn it on to access the main programming menu.

Cycle through with the toggle button until the screen reads:
AUX2: INH
FLAP:INH

That tells you the flaps are INHIBITED ---->meaning they are disabled.

Press the select button 2 times until the cursor arrow is in front of the FLAPS:

Now use the right side buttons to turn the INHIBITED mode OFF. Press the + button until the screen changes to

FLAP:SYSTEM

Done. Exit programming main menu and go dial it in using the endpoint adjustments and sub-trims.