For the second issue, you’re setting the query parameters to username and password, but for a POST request you have to send it in the body as form-encoded data. So the error message is telling you that you didn’t provide a username in the body, which is accurate.
For the first issue, I’m not sure why the password doesn’t work, but try changing it on the web and seeing if it works. It’s likely an encoding issue, so try to ensure you don’t have any special characters in the password.