Is there More than 1 User account on this computer ?
Are you Logged into the Administer Account of this computer ?
Only the Administer Account has the Privileges to perform this upGrade
Go System Preferences >> Users & Groups
What is showing and refer to image below
Further, attempting to Upgrade from Monterey 12.3
It is strongly suggest updating the 12.3 Monterey to the current version 12.6.4 before attempting the upGrade to Ventura
Links below on that specific issue
Keep your Mac up to date - Apple Support (CA)
About the security content of macOS Monterey 12.6.4 - Apple Support

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