I did some more research. Some ,ore inlcude-files were missing which lead me to install this GitHub-code
Installing libraries from a ZIP-file is described here
if you are an unexperienced Arduino-User you should start from a working demo-code
If you have installed the ZIP-library there is a demo-code
....libraries\esp8266-weather-station-master\examples\WeatherStationDemo\WeatherStationDemo.ino
before doing anything else try to compile this demo.
Then change one single small thing and compile new
If it does compile
change one single small thing and compile new
repeat
This way you will know quickly WHAT is causing the error: the last thing you did change
As more as you change and as longer as you wait with the next compiling
trying to save time
the looonger it will take to find the error eating up more time than the repeated compiling
best regards Stefan