Hello @1nsgadget, welcome to the Sonos Community!
The Sonos app shows Error 913 when it tries to connect to a shared music folder using an unsupported sharing protocol. In order for Sonos to connect to a shared music folder, it must be shared using SMBv2 or SMBv3.
Please have a look at our Support Article Error 913 when adding a music library share.
More specifically, since you are trying to add a Music Library share on your Windows PC have a look at Share your Windows music folder with Sonos which includes detailed instruction steps.
If you are struggling at any point feel free to reach out to our Support Team, as they can guide you through the process.
I hope this helps.
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