Every time I try to install the latest update on this iPad a message appears download failed also when trying to open any site suddenly message appears problem occurred the page is being reloaded

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

Of you continue to experience difficulties, you may have more success if you 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.

Check your internal storage in Settings>General>iPad Storage... and, if needed, make room by deleting some stuff.

See also this support article:--> If your iPhone, iPad or iPod touch won’t update

If the issue persists, try to update your device using a computer running iTunes (Windows PC) or Finder (Mac).

Regards

Giulio