where did you read that? if its a new install you cant assign db owner because the bes install will create the database and be assigned by default as the db owner.
You need server admin, db creator is suggested, but should be inherited as a server admin.
1) I applied only the "Server Administrators" and "Database Creators" server roles for the user "besadmin".
I noticed that the default database for "besadmin" is "master".
Is it correct ?
2) I have a problem for the assignment database roles also.
The "BES for Microsoft Exchange Version 4.0 installation guide", p. 13 section "Configure Microsoft SQL", tells to expand "databases" and to "expand the configuration database".
Which one is the configuratino database ? Do I have to create one especially for my BES installation?