I can’t open it.

Every so often do you get a file and you can't open it?  Check its file extension.  The file extension comes at the end of the name of the file and is [dot].bz, and is a key to the name of the software program that created the file.

.bz

If you go to OpenWith.org you will find a host of free programs that may point you to a "reader" program that allows you to open the particular file you are having trouble with.

tip:  FutureLawyer.