Can't login to Dashboard

Hi there, I am trying to login to my account on my wordpress website in the WPMU DEV Dashboard, but whenever I try to, it gives me this error: {"code":"rest_no_route","message":"No route was found matching the URL and request method","data":{"status":404}}

So I am unable to connect my site. I am not sure what to do.
I have purchased the pro version of WP SMUSHIT and am unable to use it - only the standard version. Please help. Thanks