YII2 how to set up environment to support a project?

Question

Yii

Good afternoon.
I took a project written in Yii2 for revision.
The project was written on the basis of Yii 2 Starter Kit https://github.com/trntv/yii2-starter-kit
How do I properly set up the environment for development and testing? Or where you can read the information you need on this particular side.
Thank you.
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Figured out, it turns out that the developer used the dev version in production and limited access to tools by ip addresses. I wonder if this practice is in the order of things?

Answer 1

There is a .env file, the configuration is written there, but at the beginning it says
YII_DEBUG = true
YII_ENV = dev
Although I took the entire assembly from the hosting, and the production version works, there is no repository and no connection with the previous developer.
Getenv() is used in configs - where does it get data from?