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 GitHub - odk-x/sync-endpoint-containers

it pulls the named folder and try’s to build the container.
However when executing the Dockerfile it first downloads a file from: GitHub - odk-x/sync-endpoint: Sync Endpoint is a server that enables data to replicated between mobile devices. It communicates with your ODK-X Android applications to synchronize your data and application files.
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 - #2 by W_Brunette