On the post.
It looks like it is this one.
There are a couple ways to handle it
The easiest would be to drill a new pilot hole directly in front of the broken one and install the post.
In front is the best choice because it will cover or at least mask the old broken one and likely have no real impact on game play in that location.
Going behind could creat a ball trap on the target.
Trying to extract it would likely do more harm than good if you are not well practiced.
Here is a crude example of what I propose. Get as close as you can to the broken post but not so close that you would run into it with the new screw once placed. Just a sliver apart
No guarantees of course but it is what I would do in this circumstance if extraction isn’t ideal.