Allow Setup Assistant to complete
If your Mac stops responding and shows a spinning wheel after you create a user account in Setup Assistant, simply allow setup to continue. The setup process will resume after about 30 minutes.
You can avoid this delay if you complete Setup Assistant without connecting to the Internet. When Setup Assistant prompts you to select your Wi-Fi network, click Continue without selecting a network. If you have an Ethernet adapter, disconnect it before you start the setup process. After you complete Setup Assistant, restart your Mac. Now you can join your Wi-Fi network or connect your Ethernet adapter, as well as set up iCloud.
If you restart your Mac during setup
If you restart your Mac during setup, Setup Assistant will appear again. If you continue setup and see a message that the user account you're trying to create already exists, create a temporary user account to finish setup.