Is there a sync between lightning .ics calendar files with Jolla phone ?

I don't think so. I am using thunderbird lightning with a radicale server (on the same host) and use caldav and carddav services for syncing to the phone. Carddav for addresses with syncevolution on the phone and with an addon (Inverse SOGo Connector) in the thunderbird addressbook. Caldav can be used with a caldav-account or syncevolution on the phone and also directly with thunderbird. Both via wlan with the phone.

it would be nice and helpful to have a web reference that describes the set-up of radicale in detail. This would most presumably simplify the Jolla-lightning sync!