Please make sure to follow the directions in the associated guideline - Pega Academy Virutal Machine User Guide . This should help with any issue you are having related to downloading and installing the virtual machine. If you do have issues please note the steps you took and try to include screenshots as they are most helpful.
As far as your second point, I was able to access this page. This is usually a browser caching issue. Please try the following steps:
Log out of all current Academy sessions
Close all active browser tabs/windows based on the browser used in Step 1
Completely clear browser cache and cookies
Restart browser and try again
If issue persists try a different browser brand or start an Incognito session in Chrome and attempt to replicate the issue.