How can I download this update? I can’t update the newest update. I just never upgraded old old iOS.

Your iPad is likely too far behind for the OTA Update via settings to be successful.

Instead, to update your iPad, you will need to connect your iPad to a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of macOS).

Update your iPhone, iPad or iPod touch – Apple Support

Update software on iOS and iPadOS devices in iTunes on PC - Apple Support

Check the iOS version running on your iPad going to Settings>General>About>Software version.

If it is erlier than iOS 11, you need to update that iPad using a PC running iTunes or a Mac running iTunes or Finder.

If you do not have a computer, borrow one from your friends, or ask for help at an Apple Store or Authorized Service Provider.

Regards

Giulio