Explanation of access rights for internal workers

We're a small translation team in a software company and we're new to Wordbee. I need some help tweaking the access right for internal workers. We have some workflows where they need to tweak the formatting of the translated file and then upload the final file before completing the workflow.

Documentation of the different Wordbee access rights is not complete and I cannot figure out how to grant translators (internal workers) the permission to download and upload target files in the Translation Editor. 

Need some help here.