Hello @david hwang Please try again and let us know if you face any issues.
Your subscription ownership looks good, but it might be an issue with the email or maybe you want to revisit the steps?
I tried the Create AAD application Pre-Req step: Create an AAD application
Below steps I tried from my subscription's Powershell cloud shell.
wget -q https://aka.ms/FarmBeatsAADScript -O ./create_aad_script.ps1 cd ./create_aad_script.ps1
Please comment in the below section, happy to help further!