I've just subscribed to Lightroom CC as my desktop Lightroom 5 crashes all the time now. When I go to top left on my desktop LR 5 to sign in and sync, I enter my email and password in the pop up box, the box goes white and then nothing happens. Any ideas?
I don't think you want to sync (sync won't work with such an old version of Lightroom). You probably either want to upgrade your Lightroom 5 catalog to Lightroom Classic 8 catalog (if you plan to use Lightroom Classic) or migrate the photos directly from Lightroom 5 to Lightroom CC: https://helpx.adobe.com/lightroom-cc/using/migrate-to-lightroom-cc.html