Galaxy error "FATAL: container creation failed"

Hello! I am new to sc-RNA analysis and I am trying to run my first project on real 10x-Chromium data. Because I don’t have the resources to run the analysis locally (my desktop has 12 cores and 64 GB RAM, but not all is available for Cellranger), I decided to find a web-based solution. I found the following tutorial, which uses a Galaxy-workflow with a similar method as Cellranger, RNA STAR solo.

I ran the workflow on multiple times, but I received the following error message every time, for every step of the workfflow

FATAL:   container creation failed: mount /cvmfs/>/cvmfs/ error: while mounting /cvmfs/ while getting stat for /cvmfs/ stat /cvmfs/main

I changed the workflow at one place: I used a custom reference genome, the latest toplevel assembly dog genome from Ensembl with the respective gtf file.

What can I do to fix this?