Endpoint container build fails

What is the problem? Please be detailed.

I am following a Tutorial for setting up odk sync endpoints and after setting up docker, i am coming to the command: docker build --pull -t odk/sync_endpoint https://github.com/opendatakit/sync-endpoint-containers.git

it pulls the named folder and try’s to build the container.
However when executing the Dockerfile it first downloads a file from: https://github.com/opendatakit/sync-endpoint
and calls the directory sync/src/main/lib. The Problem is, that this directory doesn’t exist. So it spits out an error.
How can this be? I didn’t change any code so is the downloaded code buggy or why am I getting this error?

I am running a Ubuntu 16.04 Vm and already tryed yust commenting the broken commands in the Dockerfile but i can’t image that beeing a real fix.

Check this post: ODK Sync Endpoint Setup