If your course is using LaunchPad, there should be a link in your CCLE course that opens the LaunchPad site and passes the authentication token, so that MacMillan knows who you are and what course you are in. The problem is that Safari thinks this is a security problem - and usually it would be. You don't want a web site sending you and your credentials to another site without your permission. In this case, however, it is OK - and necessary for you to allow Safari to open the LaunchPad tab.
You will see the following:
If you click the icon to the right of "ccle.ucla.edu" you will allow Safari to open a new tab with LaunchPad. Then reload the page and you should see a new tab with LaunchPad.
Safari should remember this the next time you need LaunchPad.
In Firefox and Chrome the process is similar, but the alerts and terminology are different.