First of all, I have no experience with convertors so I might be way off course here, but I'm trying to look at this logically.
It asks for a path to your former (vB) board (and only at the end). I suspect that has a config file, so then I wonder why does it need the database name and password for the vB.
Are you sure the database name, username and password are not for the phpBB board instead of for the vB board?
And 3306? is that the correct port (different applications use different ports - I use 8080 ,3307 and 3308 depending on which local server)