v65536 refers to the internal version numbering, typically indicating the first major update (often listed as v1.0.1 in the system menu). Region: [US] denotes the North American release. File Details
To use this update file, you generally need a modified Nintendo Switch or an emulator. Extract the .rar file to get the .nsp file. Download [01007960049A0800][v65536][US] nsp rar
If using emulators like Ryujinx, you can usually "Install to NAND" or right-click the base game to "Manage Title Updates" and select this file. v65536 refers to the internal version numbering, typically