There is too little information about your setup to give an answer, as there are multiple factors that could cause no playback.
It is likely a routing issue, and I suggest reading through the StudioLive Software Reference Manual for more information regarding operation with Studio One and your StudioLive mixer, Starting with Section 2.5. Link below.
https://pae-web.presonusmusic.com/downloads/products/pdf/StudioLiveClassicSoftware_ReferenceManual_EN.pdf
Contact Tech Support if you need additional help.