Can't install OS 14.6 on my IPad

If your iPad5 is capable of being updated to a more recent version of iOS/iPadOS than is currently installed, these support pages outline both the available methods by which the update can be performed - and troubleshooting should you experience difficulties:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

iOS update and restore errors – Apple Support

Be aware that your iPad may be too far behind the current version to be updated directly from iPad settings. As such, you will likely need to use a computer to perform the update. You will need access to either a PC (with iTunes installed) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.

Download and use iTunes for Windows – Apple Support

Update to the latest version of iTunes – Apple Support

Update software on iPhone, iPad or iPod touch in iTunes on PC - Apple Support

You should note that for your iPad to install an available update, its battery must be charged to at least 50% capacity - and/or be connected to its Power Adapter. Similarly, the iPad can only be updated over a standard WiFi connection - or be updated by a PC or Mac using iTunes or Finder - over a USB connection.

Your iPad is too far behind in iOS/iPadOS upgrades/updates.

If you have access to a full computer, like a Mac or Windows PC, try either using the Finder on a Mac that has the newest macOS Catalina installed OR with an older Mac with an older Mac OS, download and install the latest iTunes version ( or latest iTunes for Windows PC ), make sure the Mac or Windows PC is connected to the Internet, connect your iPad by the USB charge cable to the computer and let the iTunes application upgrade/update that iPad model, using the iTunes Software Update feature, to its current, maximum OS of iPadOS 14.6.

Best of Luck to You!

have you tried restart your iPad before download and installing? It works on me.