The installer should not be attempting to install this component on the Raiser's Edge Web Service (REWS) server.

Verify that Raiser's Edge is installed on the REWS server.

Verify that the installer is being run on the REWS server by checking the server for the presence of the following path from the local hard disk:
\Program Files\Blackbaud\Raisers Edge WebService\

If this path does not exist, then you are likely running the installer on the wrong server. Locate the REWS server and run the installer locally from that server.