Shaders for URP and Built-in RP are not compatible and you need to use the correct ones.
Online Maps automatically detects the RP being used, and the easiest way to fix shaders in an existing scene is to click the Fix button in the Tileset component's warning block.
Or you can specify shaders manually in Tileset / Material & Shaders.

We bought a copy of Online Maps and opened the Demo and Buildings scenes up in Unity 2022 only to see all Materials pink. We've run into this in another project using the legacy Standard shader.

Is there any fix for this?

Thanks,