command not found: bundle
You need to setup your server correctly getting started, then install bundler.
gem install bundler
Mina is running in a non-interactive ssh mode. That means that your full profile will not be loaded:
if you setup your server correctly and you are using a ruby environment manager please ensure that:
Mina assumes that you have set up the communication with your server through the public/private keys, not password. If you want to use the password you will have to change the execution mode:
set :execution_mode, :system