How to use figma to create the interaction effect like 'able to infinitely add new sticky note' in Figjam

Hi, I found the inetraction of adding new sticky notes in Figjam is so easy and cool, I want to use it in my design:

I am creating task list (card form) for a mobile app, and I hope when I tap the card, the plus button appear on the both sides of the selected card, and able to add new cards in both directions, then when I click other random card, this selected card will be automatically deselected.

The issues I suffered:

1. When I click other random card, the selected card can’t be deselected
2. When I press the plus button, the varriable does appear

Could I get some help, Thanks a lot!