Attach the designer to a remote gateway

Dear Supporters,

I would need to access from my home a remote gateway with the designer. Is this foreseen?. Even between different OS?. I would need to download the designer (only the designer) in a portable MAC and connect it to the gateway that I have in another machine which is a Linux OS. Is then possible to download the designer alone?. If so, why mac refuses the installation of the components (even the gateway) in version 8.0.9-osx-installer claiming that Apple cannot check it for malicious software? (adding the message: this software need to be updated. Contact the developer for more information)
Thanks a lot
Cheers
Patricia