Taking into consideration the kind of error message you have, in my view your .env file contains the placeholder value your_key instead of your actual API key.
To solve the issue my suggestion is the following:
Open your .env file and replace:
OPENAI_API_KEY=your_key
with your real OpenAI API key:
OPENAI_API_KEY=sk-...
Make sure the key starts with sk- and is copied correctly from your OpenAI account!
Happy coding!
Michela
PS 1 : Sharing your OpenAI API key is risky!! Next time do not share the link as you did.
PS 2 : More info could be found in https://docs.crewai.com/