On your Lightstream studio, click the Lightstream Logo on top left corner and select Lightstream Labs. Then scroll down and enable 3rd Party Integrations.

Click the + button next to Layer and select 3rd Party Integrations, and then click the Player.me logo. This will add a new layer called Player Overlay.

The new layer will ask you to add a Player.me overlay URL. To do this, go to your Overlay Editor. Click the Launch button on top and then select Copy Overlay URL.

Then back on Lightstream, paste the URL onto the field.