Where can I find security certificates for windows when configuring an IPsec VirtualIP connection?

Question

VPN

Hello, on my server it turns out there is no way to create a network bridge for virtualbox. And I have an edge on how to connect from it to my vpn. I created the zyxel keenetic start 2 router on it vpn (PPTP), and virtualbox in NAT mode with it (PPTP) does not work, well, I looked at Google in my router there is an IPsec Virtual IP chip rose quickly and instantly according to the guides from the office. keenetic site. I connected to IPsec from my phone and was delighted to the point of madness)) and then the hat, how can I connect to it from my windows 7? found an article like everything is clear (in English with google translator) https://wiki.strongswan.org/projects/strongswan/wi...
but at the stage of importing a certificate, I can’t understand where I should get this certificate for import, I It's nowhere to be found, not even on the website.
without this procedure, I try to connect to my vpn and gives an error 13868 "Group Policy Mapping Error"
I understand there are client programs, but terribly, you need to solve it using standard means.
If anyone has come across or knows what I'm stupid about, thanks in advance