Due to a change in Microsoft's certificate management the new Tresorit application cannot be installed on a single click, so here you can read a step by step manual on running Tresorit on Windows Vista.
1. Please download the app from here
2. Open your browser's Downloads folder and select Tresorit.exe. Right-click on it to open its context menu and select "Properties"
3. Open the "General" tab and search for the "Unblock" button in the Security section at the bottom
4. When the "unblock" is done, please click on "Apply" to save the changes.
5. Now you can close the Properties window and start the installation without any issues.
Thanks for choosing Tresorit, we hope everything will work properly, if you have any further questions, please always feel free to contact us.