Have you actually tried to update from within the CC app?
If necessary, log off and log on to your account again.
Please download and install Creative Cloud first from the following link : https://creative.adobe.com/products/creative-cloud
Once downloaded, please sign in with your Adobe ID, and Password, and then download and install Lightroom and Photoshop CC on your computer .
If your operating system doesn't support Lightroom CC, then it will not update to Lightroom CC.
What is your operating system, and is it 32 bits or 64 bits?