its not allowing me to download update

When you use the Terminal Application and use the below command

softwareupdate --list-full-installers

Hit the return key on keyboard

It should List all the available updates that is computer Qualifies to run

Does the Ventura 13.6.1 appear as listed ?

If Yes, use this Terminal command below

Suggest you Copy and paste into Terminal

softwareupdate --fetch-full-installer --full-installer-version 13.6.1

It will manually download the Full Version of Ventura 13.6.1 ( About 12.xx GB in size )

It will only place a new application called " Install Ventura " in the Applications folder of this computer

It will Not Auto Launch

When ready, launch the application like another other application and follow the prompts

In good conscience and good computer practices

Alway Make a Time Machine Backup  before doing any upDates or upGrades 

Different updates are for different Mac models. That means it is not for your Mac. Your computer knows which updates and upgrades to accept.