For security reasons, the VPN account is different than the Client Area (billing) account. The VPN login details are sent via e-mail once the account is activated. The VPN password is a strong, randomly-generated one. You can change it afterwards from Client Area - Services > My Services > View Details > Change VPN Password
The password is case sensitive.
If you tried to login to the VPN with the VPN password you received or you setup yourself and it still doesn't work, open a ticket
and we will investigate the problem.