Configuration Screen For A "Service" Type Installation
From Unofficial BOINC Wiki
This is an additional stage of installation for those that have selected a "Service" type installation. It was taken out of the main flow as at this time this is expected to be a less common type of installation.
In this step we will discuss the issues related to the "Service" type installation and the Configuration Screen for that installation.
 Configuration Screen
A User Name of one of the administrative users is usually selected and displayed when the window opens. In this case it selected the "Administrator" of the computer "EQ-2" as the account to own the BOINC Daemon when it is executing and the BOINC Daemon will use the privileges related to this account.
- The user selected must have read and write privileges to the BOINC Directory and all of its subdirectories or the BOINC Daemon will not be able to run correctly.
Enter the password for this account. Then enter it again for validation.
Update the selection check-marks.
When you are done, click the "Next >" button.
 Permission To "Logon As a Service"
As far as I know you have to say yes or the install will complete, but the BOINC Client Software will not be able to run.
 Password Check
The passwords entered are tested to see if they are the same, and if not, you will get this as a warning message and you will have to repair the error. This is a conditional dialog and you will not see it if you enter the information correctly.