What are the appropriate times for reciting the morning and evening adhkar in Sweden, given that the night is very long in winter and the sun disappears for only two hours in summer without complete darkness?

The best time for morning remembrances (dhikr) is: from after Fajr prayer until sunrise. The best time for evening remembrances is: from after Asr prayer until sunset. This does not change regardless of the length or shortness of the night. Therefore, one should perform these remembrances within this time frame.