There’s several way to approach this. One method is to setup variables within your PlayerCharacter script (or wherever most of your variables are stored). Set a trigger instance for the door, a variable (integer) that calculates your current score, and perhaps a NoHolDor variable (integer) that has the 40 point value needed to trigger the door opening sequence. Using the HUD file you likely created for the game, the text box that holds the current score can be setup with a binding that translates the data that represents your score to a text format that you can later use for validating your conditions. In Blueprints, you can take the trigger event (while referencing your player of course) and create a branch to handle the actions (true/false) while declaring a condition (e.g. integer >= integer node) with the current score tapped into the upper input pin of the node and the NoHolDor variable in the bottom input pin of the same node.
One book I highly recommend is the Blueprints Visual Scripting for Unreal Engine by Brenden Sewell. It covers this in great detail and explains what you are practicing and why it’s important. Having spent most of my time in UDK while attending school for Game Design you can imagine how ****** I was when UE4 came out less than a year after I graduated. Now that I’ve had the chance to burn through lessons and realize UE4’s true potential I love it now more than ever.