Re: Composer Create Project Fails With Stability Error
This was an issue with the repository that has been fixed for several months now. I have had no issues with downloading project files since. This issue may have resurfaced, but it's unlikely. Make sure your PHP CLI version matches the PHP version Magento recommends based on your Magento version. For example, 2.2 is PHP 7.1 and 2.3 is PHP 7.3
Can you verify what version of Magento and Composer you're using? Magento 2.3.7+ & Magento 2.4 need Composer v2 while Magento 2.3.6 and prior to that will need Composer v1.