Which site, Sarah?
Did it say they were Lr compatible?
I figured it out through a video provided by the site. It did say they were LR compatible but the instructions on the web site were incorrect. Thanks for the almost help
1. Open your photo image in the Print module
2. Tick the box to use an Identity Plate.
3. In the Identity plate window, click the drop-down arrow and select "Edit... "
4. Tick the button to "Use a graphical Identity Plate"
5. Click the button to [Locate] one of the PNG files you have downloaded.
6. You may need to click "Use anyway" if LR tells you it is too large!
7. You can re-position the PNG image by dragging from centre or by the corners. (Aspect ratio is 'fixed' i believe)
8. Reset the grid margins for your underlying photo so it fits within the PNG image.
In my screen-clip I show a 'Border" PNG image applied as an Identity Plate over my lone tree photo. I have yet to reset the photo grid margins.
You can make your own PNG images in Photoshop with any design, as long as you maintain transparency to let the photo 'Show through" Your creative ideas can be used in countless ways for an overlay!