Very new to UEFN, Followed a tutorial ( How to make custom characters with UEFN Characters )

Hi guys Im very new to UEFN, I am following a tutorial ( How to create custom characters with UEFN ) basically getting an epic skeleton mesh off the internet and adding it to a FN rig in UEFN, to make a n NPC have a different skin mesh look ect. Problem is I can get into game almost works , legs seems fine, but no animation on his arms they are stuck in scare crow poise ?? Anyone got any advice?? ( The Recon Raider mesh im using is a bigger scale than FN rig , is it this? )