Screen Share Tile works through its quick settings tile, before using it, tile needs to be added on notification panel manually.
To add tile
Please follow the following steps:
1. Pull down completely the notification shade.
2. Tap the edit button (on stock Android it is a pencil). The quick settings editing layout will expand and display all the available tiles.
3. Scroll down and find the screen share tile.
4. Drag the tile up to the desired position.
5. That’s it!