It offers you to upgrade to LR 6, which is not a free upgrade, except for subscribers to the CC cloud.
If you have a stand-alone license, then you need to buy this upgrade.
To buy the upgrade go to the UK adobe page . At the bottom, select products, scroll down to LR, click on buy, and select upgrade instead of full version.
You can buy from the following link. After clicking "Buy" change from Full to Upgrade and the correct pricing will be displayed. Then select your existing LR product from the drop-down menu.
Thank you for taking the time to reply. Very helpful
Thank you, very helpful.