Check in the applications folder for an application called " Install Ventura "
Is there such a application existing there ?
If Yes, Command key and i key should present a " Get Information " about the Application.
What size is the Application ?
Other possible issues ➡️
1 - Software on the computer interfering with the download process including AntiVirus Software
Notation: Disabling the AV Software may or may not solve the issue. Removal of the AV Software may increase the chances of the download to perform as expected.
2 - Running behind a VPN which may increase Packet losses or corruption of the download
3 - If via wifi too many Other devices using the wifi at the same time reducing the Bandwidth to your computer.
4- Best Results are via Ethernet Cable to Router
5 - Restart in Safe Mode. This will perform a Disk Repair, clear cache files and only load Apple Software, extensions and fonts. The boot up will be slow and can take some time - Normal and Try Again using the Software Update Applet in System Preferences