Issue with Assigning OnClick Event to Button in FMX Project Using Scripter

You didn't specify, but I assume ap_Classes can't be used because you are receiving errors related to VCL classes which are not present in your FMX application?

In this case, you need to register the TNotifyEvent yourself, using the event adapters. I'm not sure what you meant by this, though:

I am aware of Scripter.EventBroker, but it interacts with both Delphi and Scripter. What I need is to script the event.

Just define an event adapter for TNotifyEvent as explained in the documentation and in a few topics in this support center, like: