To enable pop-ups:

To enable pop-ups in Internet Explorer, open the "Tools" menu on the command bar and click on Internet Options, (usually at the bottom of the menu), and select the Privacy tab. Click on the Settings button in the Pop-up Blocker section, and add as an "Address of website to allow" and click Add and then Close. Click OK on the Privacy page and it will save your settings and close.

If using Firefox, go to "Tools" on the menu bar and choose Options from the drop-down menu. From the Content tab choose the Exceptions button beside "Block Pop-up windows" and enter to "Address of website" space and click "Allow" and "Close".

When Google Chrome users click on "Enter", they will see a notice at the bottom right hand corner of the page, "Pop-ups Blocked: x". Click on the notification and choose " -". Unfortunately, Chrome users will have to do this every time because, unless you are using the beta version, there is no option to allow pop-ups for designated sites.

Safari has a pop-up blocker which is turned on by default, but it doesn't appear to be at all concerned with the pop-up password window on this site. Safari for Mac OS has no per-website control over blocking pop-ups windows. Pop-ups are either blocked, or they are not. To check this setting, click on the farthest icon (the "Safari menu") to the right on the menu bar; it looks like a little gear or perhaps a flower. Check or uncheck "Block Pop-up Windows".