Plugin Saferpay Json Error

Hello

I bought the plugin os_saferpayjson and put it into operation and entered all the details from SIX correctly. However, as soon as I activate the plugin, the following error message appears (see also printscreen):
 #0 Class 'Ticketpark\SaferpayJson\RequestConfig' not found 
Can you help me further?

Greetings
Colette

Hello Collette

Could you please submit a support ticket so that I can check it?

Regards,

Tuan

Hello Tuan

I no longer receive a reply via the ticket, what is the reason?

Regards
Colette

Hello

I asked for super admin account of your site so that I can check the issue but I haven't received your response yet. Could you please send me the information via support ticket so that we can check it?

Regards,

Tuan