Having a few problems opening OmniFocusColours that I downloaded from the Omni Group staging site - any ideas?
That doesn’t look so good. You might try to delete that one and download it again fresh to a new location?
Try https://omnistaging.omnigroup.com/omnifocuscolors/ to an entirely new location.
It is normal to get a prompt that the item was downloaded from the Internet, do you want to launch? Did you get that? You should click yes to that prompt.
Hopefully something strange happened in the download and it didn’t quite all finish. I am able to download and launch it here, but there might be something unusual about your configuration, or just a problem that happened in download. Sorry for the trouble you are experiencing and I hope this gives you a few ideas to try.
More often than not you get that message due to file permissions in a bundle being weird. If you’re not afraid of the CLI, do a recursive chown to yourself and/or chmod ugo+rx the bundle.