An "Index of" directory listing for Windows 7 Ultimate ISOs typically refers to open web directories (FTP or HTTP) or archives where these installation files are stored. Since Microsoft ended official support for Windows 7 years ago, direct downloads from their official website are no longer available . Common Windows 7 Ultimate ISO Directory Listings
Once you have the ISO from a directory listing, you must prepare it for installation. Windows 7 (Ultimate) Installation Disk - Microsoft Q&A index of parent directory windows 7 ultimate iso
Searching for "index of parent directory" is a common technique to find open file directories containing specific files, like the Windows 7 Ultimate ISO An "Index of" directory listing for Windows 7