You need to copy existing data first ...
docker run -d --name lam_tmp --rm ldapaccountmanager/lam:latest
docker cp lam_tmp:/var/lib/ldap-account-manager/config/ .
docker stop lam_tmp
mkdir -p data/sess
mv config conf
sudo chown -R 33:33 data/ conf/
sudo chmod go+rx conf/
sudo chmod go+r conf/*
sudo rm conf/config.cfg
sudo cp conf/config.cfg.sample conf/config.cfg
sudo sed -i 's/^password:.*/password: admin/' conf/config.cfg