Okay well for one you are trying to integrate with vbulletin 3 right not 2? You need to select the proper integration on install for vb
3 and the error you note comes from either not inputting the correct vb
database info for vb
where asked and or not inputting the correct vbulletin table prefix on step 4 of install.
Here are common mistakes when installing with vb3 vBulletin Installation/Integration Common Issues and Resolutions.
Let me know if that helps you out.