In windows, it needs username and password only.Have a look at this page for NordVPN, if your provider has no specific certificate then you need the root cert from/for that provider
https://wiki.mikrotik.com/wiki/IKEv2_EA ... d_RouterOS
I found a setup guide for strongswan:
1. launch the app and then tap on Add VPN profile.
2. Now you’ll need to enter a VPN server address.
3. Now choose the VPN type. Select Ikev2 EAP (username/password).
4. Next, enter PureVPN provided credentials in Username and Password fields.
5. Next, check the CA certificate.
6. Profile Name: PureVPN Ikev2 (you may type anything).
Now tap on show advanced settings and type in server identity: pointtoserver.com
Finally, hit save and then connect to the newly created Ikev2 profile.
How can I setup on routeros?
thanks!