QuickOPC is a multi-faceted software, with some of its features tied to specific operating systems, and some inherently more generic. If you are developing for the "full" .NET Framework, on the COM Platform, or are using some specific product options or features such as Excel Option, you will need Microsoft Windows. In all other cases, you can also use Linux.
QuickOPC, as an OPC client, works on Microsoft Windows or Linux. The OPC server you are connecting to, however, can run on any operating system or platform, as long as it exposes the right communication interfaces. This is especially common with OPC Unified Architecture servers; many of them run on Linux, or various embedded devices and systems.
Practically all QuickOPC capabilities are supported on Microsoft Windows. You can develop .NET Framework and .NET Core applications, COM applications, or integrate OPC with Excel. Both client and server editions of Windows are supported. In addition, QuickOPC (except its UI features) also runs on Windows systems classified as "Server Core", i.e. systems with no graphical user interface for management.
Supported systems range from Windows Windows 10 and Windows Server 2012 to Windows 10 and Windows Server 2016, including Windows Server 2016 Core. Both 32-bit and 64-bit editions of Windows operating systems are supported.
If you later decide to port your project to Linux, you will not have to write it anew: QuickOPC objects and methods are identical between the operating systems.
QuickOPC runs on various Linux distributions if you target the .NET Standard development platform, by means of the .NET Core runtime. On Linux, OPC Unified Architecture and OPC XML-DA are directly supported. The programming is identical to that on Windows for .NET Core - in fact, there is just one set of QuickOPC assemblies and/or NuGet packages targeting .NET Standard.
Features specific to Windows user interface, such as Live Binding, and browsing dialogs and controls, and not available under Linux.
Footnote & required disclosure: QuickOPC (including its Options) is a software development kit (SDK) for development of OPC clients. Installing QuickOPC or its Options does not change system settings.