OnTriggerEnter instead of activate (will automatically run when you enter the volume). you also need a condition filter to only allow the action to happen if the akActionRef is the player, or else any NPC that strolls through it will force you to move even if you arent in it
if you want it to work like a door with a prompt, you would use OnActivate, but you would then need to select Player Activation in the "primitive" tab, and your trigger activator has to have a name or else it wont appear selectable.