I tried playing as the Hillbilly, Clown, and the Oni and it wasn't working. it gave me the option to grab, but every time I went to go get it, it would do the attack action. Please help.
Picking up a crown as a Killer does trigger the attack animation, but you're not really attacking. To confirm if you picked up the crown, check for a golden VFX on your screen. If you did get the "golden glow", the crown should be awarded to you once the match is finished unless some bug occurred.
I was confused at first too, but when You get close to the Crown You get the "[Space] Pick Up" option. Just pressing Space doesn't work though, You need to hold the Space button till all the animation plays out and You get the crown. As @FichteHiro said, You'll know when You're done when golden glow appears on Your screen.