After clicking on the "Download" button, and registering/logging in if necessary - you should see the following screen:

Click on the link "LPCXpresso IDE for Windows v8.x.x" (or Mac/Linux versions if appropriate), and this should present you with a EULA to agree to. After doing this, you will have access to the various v8.x installers....

Select the ones and download. The servers for this are external to the NXP network, and seem to be up and running at the moment. If you are still having problems, please screenshot exactly what you are seeing.
Regards,
LPCXpresso Support