Did you install the package? Then please use local paths instead. Connecting to network shares does no longer work with DSM 7 and newer. Why even try and use network share for local folder on the same NAS (at least that is now what you seem to try)?
So then you should have been asked about where your music is (chose a folder) does this folder work for you? You should also have seen instructions about the rights you have to set on other folders on your NAS if you need Roon Server on your NAS have access to them. Please make sure you actually run the latest version of the package, compare to: Synology DSM7 – RoonOnNAS (20220216).