"Failure to install this Update will prevent Windows Update from patching your system with any future updates starting with updates released in May 2014,"If the users have disabled the automatic updates features then windows store doesn't show any updates for you. If you wish to make it manually here is the some steps you have to follow.
Head over to the PC Settings (Charms menu -> Settings -> Change PC Settings) and in the updates and recovery section, go to Windows update and click Check for updates and install the KB 2919355 update. (If it is not showing up, you might have missed some previous updates, which are a pre-requisite for this one, install those first to get this one).
Some recommended thing you have to know is that,
- If you are still running windows 8 though, you do not need to update your machines. You will be provided with security updates till Jan 2016. Windows 9 will most probably be available by then.
- Windows Server 2012 R2 users also need to apply this update to keep receiving patches and fixes in the future.