Invalid Username/Password

i have installed both of the plugins and followed the instructions but when I am trying the login API on postman it is saying “Invalid username or password” but the username and password both are valid.

i am trying this URL: https://mywebsite.com/api/auth/generate_auth_cookie (POST)

and this is the response I am getting:
{
“status”: “error”,
“error”: “Invalid username and/or password.”
}