I have an existing project that I want to start using version control. My project doesn’t have the version control icon in the top left like the Unity manual states. Also in Project Settings->Version Control I’ve got it on PlasticSCM but there is an error under it that says Not Connected. Version Control plugin error.
Hi,
What Unity version and “Version Control” plugin version are you running right now?
Can you share some screenshots of the error so we can get more context on the situation?

Hi,
You are running a 2 years old version, can you update the plugin to the latest first?
Hi, I think you are using the legacy plugin. You will need to install the Version Control package via the Package Manager.