The plugin cannot be installed online

The plugin cannot be installed online

Download the case project and report an error

Hi @coke2025, welcome to the community!
Our packages are hosted on github.com, so your system will need to be able to contact that server. Specifically, for the latest release, you’ll need to be able to download from here:
https://github.com/CesiumGS/cesium-unity/releases/download/v1.15.2/com.cesium.unity-1.15.2.tgz

Can you check if that is working on your system / network?