Hi,
1: your class will have to be a monobehavior,
2: you'll need to make that variable public, and then you can use the "get Property" to get it from that script and store it in a Fsm variable,
3:You can create an "object" variable, select its type to be of your script class, and drag and drop that component onto this variable, and in the "get property" action, you reference that "object" variable, and your variable will be listed
If that's not clear, I'll make a working example.
Bye,
Jean