The eero app can be used with devices that run either:
Android 7.0 or later
iOS 15 or later
As well as those operating systems, the device must have Bluetooth 4.0 or better enabled on the device and a mobile data connection.
You can find and download the eero app free of charge.
Android devices - Google Play Store
Apple devices - Apple App Store
Search for 'eero wifi' and download the app that's been developed by 'eero LLC'