The trace is not set up right. You’re tracing towards the centre of the world 0,0,0 so it’s quite likely that you’re missing the platform (no clue how your world looks like). Compare it to mine - trace down, from the player. I’ve assumed the player is not a giant and 200 uus (2m) is enough to reach the platform they’re standing on.
The rest looks spot on.
Also, I am casting to my platform blueprint not to the group actor is that correct?
Cast to the platform - we’re assuming you’re standing on that type of actor, otherwise, the cast will fail, which is also fine.