Error get license key

Hi,
I can not get a key license. It does not send the email, in the console I get this error:

VM790:1 Uncaught SyntaxError: Unexpected end of JSON input
at JSON.parse (<anonymous>)
at Object.success (admin-nbdesigner.js?ver=2.3.0:141)
at i (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,wp-a11y,jquery-ui-widget,jquery-ui-position,jquery-ui-core,jquery-ui-mouse,jquery-ui-resizable,&load[]=jquery-ui-draggable,jquery-ui-menu,jquery-ui-autocomplete,jquery-ui-slider,jquery-touch-punch,iris,wp-color-picker&ver=5.2.2:2)
at Object.fireWith [as resolveWith] (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,wp-a11y,jquery-ui-widget,jquery-ui-position,jquery-ui-core,jquery-ui-mouse,jquery-ui-resizable,&load[]=jquery-ui-draggable,jquery-ui-menu,jquery-ui-autocomplete,jquery-ui-slider,jquery-touch-punch,iris,wp-color-picker&ver=5.2.2:2)
at x (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,wp-a11y,jquery-ui-widget,jquery-ui-position,jquery-ui-core,jquery-ui-mouse,jquery-ui-resizable,&load[]=jquery-ui-draggable,jquery-ui-menu,jquery-ui-autocomplete,jquery-ui-slider,jquery-touch-punch,iris,wp-color-picker&ver=5.2.2:4)
at XMLHttpRequest.c (load-scripts.php?c=1&load[]=jquery-core,jquery-migrate,utils,wp-a11y,jquery-ui-widget,jquery-ui-position,jquery-ui-core,jquery-ui-mouse,jquery-ui-resizable,&load[]=jquery-ui-draggable,jquery-ui-menu,jquery-ui-autocomplete,jquery-ui-slider,jquery-touch-punch,iris,wp-color-picker&ver=5.2.2:4)

Also, when the WordPress plugin is installed it becomes very slow. This is normal?
Thank you.
Regards,