You need to download pro from your personal pro download page. Go back to the email you received & find the link they gave you. Open that page & bookmark it.

I downloaded pro fine just one minute ago.

If you can't find that email, then go to the LW support page Lime Wire » Support, click on the pro support & click on the Download/Update LimeWire PRO link, then enter your email address you used to get pro with. If it doesn't work then either your support period has finished or you didn't buy pro from the official site (a scam site instead.)