Assuming you are using Internet Explorer:
-- Open it.
-- On the menu, select Tools, then select Internet Options.
-- Select the Privacy tab, on the Pop-up Blocker, check the box.
-- Press the Settings button, and check the box "Show Information Bar when a pop-up is blocked.
IE should now show a yellow band at the top of the webpage where the pop-up was blocked. Click on the yellow band, and you can choose to allow pop-ups from that website. This should allow you to download a flashplayer.