you can start a SimpleVM during workshop preparation based on that resenv image, then log in to it, pull the containers and download the data, then create a Snapshot of the VM (give it name) and then use that snapshot as the base image for all workshop VMs.
For de.NBI specifically
please note that if the data used for the workshop is too large (current images come with 50GB total disk space), please contact us beforehand. We can prepare volumes for each of the VMs beforehand
de.NBI specific instructions are at https://cloud.denbi.de/wiki/simple_vm/workshop/ and https://cloud.denbi.de/wiki/simple_vm/snapshots/
pre-configured image: https://github.com/deNBI/resenvs/blob/master/vscode/cwl.yml
@nilshoffmann writes
For de.NBI specifically