You can cast a line trace from the cursor to straight down to the ground and detect if the hit object is the one you’re looking for.
Here’s a tutorial on converting the cursor location into world space:
(Note that you should set the end location of the line trace to ( [Cursor X Axis], [Cursor Y Axis], -1000) to make it go straight down, being different from the tutorial. If your camera is facing straight down that is, if not, you should of course take the angle into consideration.)
If there are other objects on top of the surface we’re gonna be checking, you can make our line trace detect only certain objects by using a custom trace channel. Here’s a tutorial on it as well:
Finally, you can add an actor type tag to your surface and use the Actor Has Tag node to detect if the line trace hits it, or just use the display name. Though make sure to add an actor type tag for the tag one to work. And to check the hit actor, you can simply break the hit result of the line trace.
Hope this helps! 