Hi, you mean you have registered an account on http://account.spinnerchief.com ? And cannot use that account?
If there is special char in your password that maybe lead a wrong in api program. So only use 0-9 and a-z in your password.
There is a connection problem between your server and our server, i have checked our API server, it works perfect.
Please go to check your server, or can you log in this site with your account: http://account.spinnerchief.com and you must activate the curl information in your wordpress.I think you'd better ask the MainWP support about how to set SpinnerChief in MainWP, they should know this better than us.
And I am sure MainWP works with SpinnerChief, because some others users are using it too.