In your Overlay Editor, click the Launch button and select Copy your overlay URL.

Then on OBS Studio, click the + button in the Sources area and select Browser. Select Create new, then click OK. In the properties window, paste your unique Overlay URL on the URL field, then set the Width to 1920 and Height to 1080. Click OK when you are finished.

Note: If you use more than one overlay on different scenes, we also recommend enabling Shutdown source when not active and Refresh browser when scene becomes active so the overlay does not become inactive.