It means that you have to string them together like you have so that it runs through linearly, so you cant just run off to multiple different locations.
Simplest way for you to achieve the reverse is to duplicate everything you have there and connect the OnActorEndOverlap to reverse. It’s an incredibly messy an bad way to do it but it would achieve your desired result. Personally though I would change things around a bit and use array’s and loops. If you create an array of all your doors and do a forEach loop through them all, setting their location and having a delay before doing the next 1 like you currently have then you should be able to do it quite easily