With changes to Gatekeeper in High Sierra it is now much more likely that OSX will try to quarantine the sim. When it does this the sim is translocated to a read only disk and this will make access to it's online database impossible.

The effect in sim of this is usually that the quad will rev it's motors but not take off.

The fix to this is different for different OSX systems but in general - downloads is no longer a safe folder to run the sim from and invokes quarantine.
On some OSX systems you can run from applications folder and on other OSX levels this also creates a quarantine - we recommend not running from downloads, trying documents folder or just a new folder inside your home folder. If this doesn't work then try moving the launcher to the applications folder.

For more tech savvy OSX users you can remove the quarantine flag manually.....

First check the flag is set ...

sudo xattr /downloads/velocidrone/launcher.app        (use the path to your launcher this is just an example)

If it is quarantined it will return com.apple.quarantine

Remove the quarantine flag as follows

sudo xattr -r -d com.apple.quarantine /downloads/velocidrone/launcher.app   (again substitute your path to the launcher in here)

We also have another generic article on this issue here  which has some additional advice-- > https://batcavegames.freshdesk.com/solution/articles/16000082828-quad-controls-work-in-controller-setup-but-in-the-game-the-quad-won-t-take-off

It would help greatly if Apple could stick to one security policy rather than maintaining multiple different policies across it's different OSX levels - but it seems this is too much to ask and as such we find ourselves having to provide multiple different levels of advice to cope with Apple's fragmented security policies.