The best free tool with un-limited possibilities is Toogit's project management tool.

It provides you options to

define tasks

Assign tasks to team

tracking via email and notification time line

define deadlines

define criticality of an issue

add comments

Hi, I know that it can be pretty challenging to make a choice. Still, I think you can give a try to this reliable management tool for freelancers https://protemos.com/tms-for-freelance-translators.html . You see, It is always better to work with some dedicated team to build a successful product you need with extensive knowledge and work experience. I am pretty sure you`ll take the best decision. Good luck