Hello,
i am new in Sailfish OS. It looks great but i cant open Whattsapp.
Whattsapp is saying that may Phone Date and Time is not correct. (but it is).
I tried out several things.
New install of Android Support, Store, Whatsapp and enough restarts.
Has anyone an idea?
Thanks
Depending on what Xperia device you have you may be able to access the Android setting and manually set the time for the Android layer:
https://jolla.zendesk.com/hc/en-us/articles/360013922680-Accessing-Android-settings-
I am on a Sony Xperia X an can not set Time and Date on the Android Layer
How did you install WhatsApp? Where did you get the apk file from?
After Searching for WhattsApp instead of Whattsapp in the AndroidStore it Shows a higher Version
that works.
I am very happy because now i can really forget Google Android 
This is a modded unofficial version of WhatsApp you link to (crap/spy/malware? similar to find something in store like WhattsApp).
Something I would not touch!
i also suggest not to use any modded version of whatsapp. and try to update whatsapp from the play store or only trusted websites.