I am trying to install Ubuntu on windows using Windows subsystem for linux, but on store the button is grey
You are trying to install the Windows 10 1709+ Ubuntu WSL on a Windows 10 1703 installation. That will not be possible.
What you actually want to do, if you want to install WSL today on a Windows 10 1511+ to Windows 10 1703 installation simply do the following:
- Enable Developer Mode
- Install Windows Subsystem for Linux Beta
how can I enable it?
You cannot enable it. What you have found can only be installed on a Windows 10 build 16215 or higher installation. You should simply wait until 1709 is released or use an Insider Preview build of RS3 (aka 1709) if you cannot wait.