If you would like to download the Firefox browser go to Firefox  to download load it.
Then install the downloaded file.

If you would like to install the "download them all" extensions click on the link.
Then click on the Install link on the web page.
Restart the Firefox browser.
Go to the MEAC  webpage where you would like to download lots of files.
Right click and select download them all.
A list of links will appear and checkmark the ones you would like to download.

Now sit back and wait for them to download.