Cannot access figma design file generated with a help of Figma AI in “Developer Mode”

Hi Fedir, thanks for reaching out here in the community! I had a quick look and saw that our support team has already replied to you directly.
Just sharing the key points here as well, in case others have the same question:

Since you're working in Figma Make, it's good to know that Dev Mode isn’t available in this environment like it is in Figma Design. That said, you still have a few options for working with code:

• Review and Adjust Code: Next to the preview, you'll find the code editor. You can click on it to review the generated code. If you need to make adjustments, you can directly edit the code within this editor.
• Download the Code: To download the code, look for the "Download" button within the code editor section. Clicking this will allow you to save the code to your computer, enabling you to continue development locally.

For more detailed guidance, please check out the Figma Make Help Center.

Hope this clarifies!