It's very simple, first, get it :
docker pull camillebaronnet/zimbra-activesync
And run it :
docker run -d \
-p 80:80 \
-e ZIMBRA_HOST=myemaildomain.tld \
-e ZPUSH_URL=myzpushdomain.tld \
--name zimbra-activesync
camillebaronnet/zimbra-activesync
Clone from the Github project, build it and launch it
git pull https://github.com/camillebaronnet/zimbra-activesync.git
cd zimbra-activesync
docker build -t zimbra-activesync .
docker run [...] zimbra-activesync