When I select VPN Connectivity > Application of VPN connectivity on the cloud computing control panel, an error page appears "Not found".

It becomes an error (Not Found) when applying for VPN connectivity from a user who does not have the service authority of Arcstar Universal One.
After granting the service authority of Arcstar Universal One to the corresponding user on the business portal, please apply for a VPN connectivity. Or please apply for a VPN connectivity from a user who already has the service authority of Arcstar Universal One.

Please refer to the following FAQ for the operation method on the business portal.
FAQ - Tell me the operation/specification of Business Portal.