I'm trying to generate an access token and it generates fine when using the "form-data" option in post-man. However, we have a client who is only able to use x-www-form-urlencoded in their post request and using this method returns the below error:

{
    "error": "invalid_grant",
    "error_description": "authentication failure"
}

I am including the password and security token (concatanated) in the request and I cant figure out why it would work using form-data but not form-urlencoded

Any help greatly appreciated!