Symptoms

System Tray shows that the ZeroTier was properly Joined and status was "OK", however, it just doesn't connect to the server.

Found Missing or Disabled ZeroTier Network Adapter 
Control Panel > Network & Sharing Centre > Network Adapter, found missing ZeroTier adapter or ZeroTier adapter disabled.  

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The solution 
Open Control Panel > Network and Internet > Network and Sharing Center > Change adapter settings 

Right-click "ZeroTier One" adapter > Enable it 

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