1st step: Download the forms, save it to your computer.
(Do not try to open it right after downloading it from whatever browser you used.)
2nd step: Open your latest Adobe Reader program, click File and Open, browse the file you just saved from step 1, and click/open the file from there.
Let me know if this works.
Note: If you are using a Macbook, you may have to downgrade your Adobe Reader.