I have just gone through this with another community member privately and we got it to work. It took a few days but we got there in the end.
The above post yours on “How do I set up a rubbish reminder” will walk you through a lot of the settings.
One thing you could try first as it is a lot easer to test if you can receive a notify message (even if you know you can as this blueprint has the same format) it to download my 
State Notifications & Actions blueprint and just use a light or something with an ON / OFF state. you can turn it ON and OFF to receive messages. Once you know it works move to this blueprint.
also could please provide us your YAML of the automation? This YAML code are the settings you have selected in the automation so I can help. To do this go into your automation, top right 3 dots, Edit in YAML, copy all the code, come back to the forum and in your reply at the top tool bar click on “</>” and paste code in there.
And we will also need a screen shot of your calendar event.