Shadow on Nexus 6

Goodmorning everyone. I did some tests to see the differences between render via PC and via Smartphone.
Via smartphone do not appear shadows. Is there any particular setting to be activated?
I have a nexus 6.

Hello.

Nexus 6 doesn't support depth-texture extension, which we use for shadows generation. You can visit http://webglreport.com/ and check it.

however, we're thinking about a workaround for such devices

Thx!