I’d say the natural choice would be to look at the official /e/ homepage, use the official installation instructions that point to the official download location.
Start here: Get /e/ OS - e Foundation - deGoogled unGoogled smartphone operating systems and online services - your data is your data
There are other community written guides like A clear guide to install /e/OS on your Fairphone or probably also some in the /e/ forum at https://community.e.foundation
In case something doesn’t work during installation, maybe someone else has already reported/solved the problem. In that case you could look at
https://forum.fairphone.com/search?q=fp6%20%23eos-murena%20order%3Alatest