"error": "invalid_client" while using Django OAuth toolkit

I was following the steps mentioned in the documentation for django rest framework. I'm not able to proceed from step 4. As mentioned in the documentation,

curl -X POST -d "grant_type=password&username=<user_name>&password=<password>" -u"<client_id>:<client_secret>" http://localhost:8000/o/token/

I have changed the above variables with my values.

curl -X POST -d "grant_type=password&username=admin&password=admin123" -u "5hKeHNtF3EKy3uCpJqaAe3mU2bGZTgJhsKKxIuAQ:pbkdf2_sha256$390000$VFcCOjIZkBFObellddDgKA$DXovC1UiuxRQ0KN/lARIdQmXcj8dnoJofkznmkkqsZY=" http://localhost:8000/o/token/

I tried to import the curl on postman and Im getting this error

Then I tried running the curl on Insomnia testing tool, and I got the request configured as in the screenshot.

Then I click send and I got an error

SO i changed 'Content-Type' to 'Form URL Encoded'

Now I'm geting an error

{
"error": "invalid_client"
}

I tried running the curl in shell also, and I'm getting an invalid syntax error

I'm stuck with this and don't know how to proceed with this. Please lend me a hand.

Thanks in advance...