How to use Catalina window snapping feature?
There's no &quot;translucent box&quot; in Catalina, that was for previous versions of macOS.  To do that, you would click and hold the green button.
Catalina uses the &quot;hover&quot; method.  Hover over the green button and you'll get a popup allowing you to select &quot;Full Screen,&quot; &quot;Tile Left,&quot; and &quot;Tile Right.&quot;
Personally, I've found macOS' window snapping feature a bit light on functionality.  I recently started using BetterSnapTool that allowed me to create custom snap areas anywhere on my desktops (multiple monitors).  I can even assign shortcuts so that I can snap my open windows to the preset monitor and size.  It costs $3, but (IMO) it is well worth it.
I've tested various other window managers that didn't work for me, but you might get better mileage out of them

Magnet ($3).  Intuitive and very useful. I couldn't use it because it conflicted with Think or Swim trading platform.

Spectacle (Free).  Worked well in El Capitan, however it's no longer maintained and was crashing in Catalina, though it may have also had a compatibility issue with Think or Swim.

Moom ($10).  Moom is short for Move and Zoom.  It works on a grid system and has the ability to remember layouts

Divvy ($14).  Another grid based window manager .  It allows you to &quot;divvy up&quot; your screen into snappable areas.

Rectangle (Free). Allows you to resize windows with keyboard shortcuts.  There's about 20 predefined shortcuts, and no way to create custom snap points/sizes.

Hookshot ($8).  Based on Rectangle and from the same developer. Uses modifier keys and mouse gestures to snap windows.