Keyboard, mouse and screen size

Keyboard

While the Windows desktop has the focus, keys go to Windows. macOS keeps a few, such as ⌘Tab.
⌘ acts as Ctrl, so ⌘C and ⌘V copy and paste in Windows. Prefer the Windows key? Turn off ⌘ acts as Ctrl in the desktop’s Advanced settings.
Ctrl+Alt+Del has a button in the bar.
Click the sidebar to get ⌘1 to ⌘9 back for switching.

Screen size

Fit the window (default): the Windows desktop follows the size of AirSCP’s window.
A fixed size, or Full screen. Full Screen in the bar (or ⌃⌘F) switches at any time.
On a Retina screen, Windows gets the full resolution and scales to 200 %, so text is sharp.

Advanced settings: display, Retina resolution and ⌘ acts as Ctrl

Tips

⌘Q still quits AirSCP (it asks first while Windows copies files).
Audio, printers, smart cards and several monitors aren’t supported.