As long as this is a recent version of LiveCycle, the only certificate you might need would be for Reader Extensions. And you can complete your installation without it and add it later (in AdminUI) if you like.
Check your license certificate to see if your org bought that piece. It might be listed as 'Reader Extensions' or 'ARES' or something similar. If they did buy it and you still can't see the certificate (a .PFX file) then you should contact customer service and have them make sure it's in there and that you're connecting to the proper account.
To do that, email customercare@adobe.com and include your details. (Name, the Adobe ID you're using for licensing.adobe.com, any order number information you might have - and a copy of your licensing certificate if you have it. More information makes it easier to find you.) Don't send any passwords.