From the boiled water forum (and Paradox forum too)... 369 MB download.

Release 1.0.1 Notes, 5/2/2018

Trial fix for an issue where save games could sometimes fail to appear upon re-launching the game.
Trial fix for some occasional crashes when loading back into the sim-game scene.
We now immediately apply changes to the windowed mode and fullscreen monitor selection settings.
Added the ability to change the Callsign associated with your multiplayer profile.
Fixed issues with the Vsync setting sometimes not applying correctly.
Setting Vsync to be ON by default.
Capping framerate at 120 when Vsync is OFF.
Fixed an issue where redeeming a valid unlock code could cause a long loading screen.
Fixed an issue where 'Mech model variants unlocked using an access code could be seen clipping through other Argo UI screens, after selecting the unlocked 'Mech in the Mech Bay.
Fixed minor graphical issues with the pre-order Shadow Hawk Umbra skin.
Fixed an issue where enemy AI could sometimes act slowly during Defend Base contracts.
Improved loading sequence stability when alt-tabbed.
Support for non-standard Steam install directories (directory paths with special characters like "=" in them.)
Removing debug F6 pilot-injury hotkey.
Adding version number display to the Main Menu.
Adding protections for errors in the GOG Galaxy client when playing through GOG.
Making DirectX 11 a required component in Steam and GOG installers.

its just sitting there in galaxy, not really downloading. (downloading ..... checking files ..... 0% ......)


edit = ok now its finally updating thanks.!

Is it available as normal installer too, or I need galaxy for update.

Updated installers usually take a few days to appear. If you're in a hurry, use Galaxy to update the game. You can close it afterwards (or uninstall it, if so inclined), as it's not needed to run anything beyond the updater.

Not yet. You get updates basically the same time as Steam if you use GoG Galaxy, the installer versions take longer for them to make and QA test the installation process.