Roughly: "Otherwise, I'd be concerned for you, if I were in Croatia".

Thank you. We have the same in Croatian - tikati.

If you know German you will know this it is like the difference between du and Sie.

It means: "I would like you to call me XXX, when we were together in Croatia" reeplace XXX with his/her name. "Tykat se" in English is something like to be on friendly terms, not to call each other with their surname. Opposite is "vykat se" which means you address a person as "Mr/Mrs" YYY.