The official firebase website has a link to download the latest version of their SDK for Unity. The page is here and links to the following URL.

Download Latest Unity SDK
https://firebase.google.com/download/unity

Older versions

To download older versions, you can use a direct link like below.

Download arbitrary Unity SDK
https://dl.google.com/firebase/sdk/unity/firebase_unity_sdk_X.YY.Z.zip

For example to download firebase SDK version 6.15.2, the direct link would be:

https://dl.google.com/firebase/sdk/unity/firebase_unity_sdk_6.15.2.zip

This information came from this Github issue.

No Such Dev

Software Engineer | Indie Game Developer | Founder of No Such Studio. Follow me to learn how to make video games with Unity. http://www.nosuchstudio.com

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