Hello,
It took me some time to create Alfresco Docker images on the arm64, so if anyone is interesed how to do it I posted on Github a detailed guide:
https://gist.github.com/howkymike/d2ad4e81298e2408511a14cb731441c3
It is compatible with 7.1 and 7.2 Alfresco Community versions.
Feel free to contribute 
