Airplay Display cannot be turned on

Hello taliaslomanmoll, 

Thanks for reaching out to the Apple Support Communities. From your message I understand that you're wanting to be able to use AirPlay with your Mac and iPad. 

With AirPlay you can connect your iPad to an Apple TV or AirPlay 2- compatible smart TV. You can use AirPlay video from your Mac with an Apple TV or AirPlay 2- compatible smart TV, also. You can also mirror or extend the display of your Mac to an Apple TV or AirPlay 2- compatible smart TV. This article will show you the steps to take for these different options: How to AirPlay video and mirror your device's screen. 

If you're wanting to use your iPad as a second display for your Mac with Sidecar, you'll first need to be sure that they meet the system requirements listed below: 

Mac using macOS Catalina

• MacBook Pro introduced in 2016 or later
• MacBook introduced in 2016 or later
• MacBook Air introduced in 2018 or later
• iMac introduced in 2017 or later, plus iMac (Retina 5K, 27-inch, Late 2015)
• iMac Pro
• Mac mini introduced in 2018 or later
• Mac Pro introduced in 2019

iPad using iPadOS 13

• iPad Pro: all models
• iPad (6th generation) or later
• iPad mini (5th generation)
• iPad Air (3rd generation)

Additional requirements

• Both devices must be signed in to iCloud with the same Apple ID using two-factor authentication.
• To use Sidecar wirelessly, both devices must be within 10 meters (30 feet) of each other and have Bluetooth, Wi-Fi, and Handoff turned on. Also make sure that the iPad is not sharing its cellular connection and the Mac is not sharing its Internet connection.
• To use Sidecar over USB, make sure that your iPad is set to trust your Mac.

You'll find these requirements at the bottom of this article, which includes how to set up and use Sidecar: Use your iPad as a second display for your Mac with Sidecar. 

Cheers!

Hello taliaslomanmoll, 

You don't actually turn "on" AirPlay. With the "Show mirroring options in the menu bar when available" selected, the icon will appear in the Mac menu bar when there is a device it can mirror with. When there is a device it can mirror with, you'll see "Off" and then the name of the device under Settings > Display >  AirPlay display (the setting in your screenshot). If there is no device showing, then it's not seeing any. Follow the steps under, "Set Sidecar options," in this article: Use your iPad as a second display for your Mac.

If you're still not able to use Sidecar, try restarting your Mac by going to the Apple Menu in the top left corner of the screen and selecting Restart. You'll also want to restart your iPad following these steps: Restart your iPhone, iPad, or iPod touch.

If the issue persists and you find you need more assistance, Contact Apple Support.

Enjoy the day!