Honestly, just use git. My team use gitlab. It's a great setup that can be used on a private server inside a private network, that everyone can use/connect to.
It allows the team to do all the standard stuff, using issues, issue tracking, milestones, resolution times etc, assingments, documentation, each issue and code segment can be commented and viewed through an online GUI. It's also easy and simple to use. :).
You can also setup "runners" and "pipelines" for deployment management and automatic testing. :)