On Virtualbox 5.2.12 with 3 gigs ram and 30 gigs virtual disk, FAT file system, the installer boots up ReactOS, but then on the reboot, it hangs on the ReactOS logo. :-/

Update: rebooted, pressed F12 and selected Debug. Now it works...

rebooted in normal (default) boot, works now too. Except that the new hardware wizard fails installing any drivers for audio and ethernet.

Could install Virtualbox additions. Though weirdly, the mouse stopped working, so I had to use the keyboard for that.

After that, the mouse worked again.