Thanks for posting and welcome to the community.
Airplay 2 for SoundTouch is currently in development, for now you will be able to use Bluetooth as an alternative method. I hope this helps.
Hector B - Community Support
Jan 15, 2020
I noticed that today Bose released an update through the soundtouch app that adds airplay 2 functionality to all soundtouch devices except the soundtouch wireless link, if there's a date for adding airplay 2 support to it?