Thank you for the screenshot. It is very helpful.
You probably already know it's easy enough to simply disable Notifications from that app by toggling the "Allow Notifications" switch, but I understand your concern about having an app on your Mac that you do not recall installing and are unable to find.
In this case I suggest going to (Apple menu) > System Preferences... > About This Mac, then click System Report.
In the left column, under Software, click Applications.
Along the top you will find a column headed "Application Name" that you can sort alphabetically. Those are all the applications installed on that Mac, many of which may not be easily found using the Finder. Scroll through that list and determine if you can find it.
If so, select it. The field below will reveal its Location, and the path where it exists. Example below, using the About This Mac app:
Let me know if you are successful finding it that way, or if you still can't find it.