Redmine

I am trying to install the plugin 'redmine_crm-4_2_4-light' in our enviroment.
I followd the steps in the README-file: * Copy redmine_contacts plugin to {RAILS_APP}/plugins on your redmine path * Run bundle install --without development test RAILS_ENV=production * Run rake redmine:plugins NAME=redmine_contacts RAILS_ENV=production

The first warning i get is the following:

"Don't run Bundler as root. Bundler can ask for sudo if it is needed, and installing your bundle as root will break this application for
     all non-root users on this machine."

In my app-directory the only user with permissions is the root user. The apache group (www-data) has execute permissions on some directorys. I guess it needs execute permission on the folders "/plugins/<plugin>" and "/public/plugin_assets/".
It seems that all dependencies are installed correctly + the root user is the owner of the Gemfile.lock file (which the gems are loaded from?). I can "bundle update" without any problems.

When Installing the Plugin I get the error (the error can be found in the attachments).

Here are some more informations:
Environment:
Redmine version 3.3.1.stable
Ruby version 2.3.3-p222 (2016-11-21) [x86_64-linux-gnu]
Rails version 4.2.11.1
Environment production
Database adapter Mysql2

I installed a docker container with the following image "redmine:3-passenger" which was the closest to our enviroment:
Environment:
Redmine version 3.4.10.stable
Ruby version 2.4.6-p354 (2019-04-01) [x86_64-linux]
Rails version 4.2.11.1
Environment production
Database adapter SQLite

In the container I installed the plugin without any problems.
Maybe someone has any idea.

best regards
Ramon