What if my device does not allow passkeys to be set up because it is administered by a third party? (e.g. for work mobile phones)

It may be the case that your device is administered by a third party (e.g. because it is a business phone) and it is therefore not possible to set up passkeys. In this case, there is unfortunately no way to save a passkey and you will need another device that allows you to save passkeys.