@MatteoDefanti_twitter understood. Especially when you look at the more complicated example that's already been finished for you, it can feel daunting. At the same time I think we benefit seeing something more complicated.
What helped me to get started and not get lost with the actors was tracing/logging inside each actor (have a logger that writes to a file in each actor for instance). Then after some interactions review the logs.
Another thing that helped is writing tests for actors I was defining.
and most important, and it's emphasized by Jon, it helps when you start thinking of messages and message flow first, those are the keys in actor based modeling. Sort of helps keep the picture clear.