The PS-49 is a MIDI controller and thus does not inherently "sound" like anything.
You would need to configure a piano sound within Studio One.
For example, you could drop in one of the piano presets found in the Presence instrument.
If you need help configuring your PS-49 to work within Studio One please see the link below:
*NOTE: This guide is indicated for Studio One v2 but the process will be the same in v3.