New Installation - SyncService - Existing Database

Hello, we started to use ARS two weeks ago. We had no problem to install the Admin Service. Now I've tried to setup the SyncService and our Database guys already create an empty database for that. But during installation I get the following error:

Error occured when configuring Synchronization Service.

Details: The configuration database name you specified already exists. Specify a different name.

How can I use a pre-created database during setup of SyncService?

Thank you!