The database ACL is set to give -Default- Manager access but it does have "Enforce consistent ACL" enabled, which could pose problems but for the -Default- setting. If you're having problems opening it, it isn't because the database can't be opened, but something else is obviously going on. Make sure that you extract the superntf*.nsf file into your local Notes\Data\ directory structure and try again. Trying to open it from some other random directory Also note that versions prior to 6.5 are not supported, although I think you could open it in 6.0 with no obvious problems.
If that doesn't get you in, let me know what OS and Notes client versions you are running.