Installation of SNAP
From AWF-Wiki
Download current [SNAP Version 7.0.0]. Choose the correct version for your Operating System (table row "Sentinel Toolboxes"). If running in Windows, install as Administrator. Do not configure to use snap with python (executable).
Start SNAP Desktop. Install an additional plugin: sen2cor version 2.8.0 In SNAP (Menu -> Tools -> Plugins -> Available plugins check Sentinel-2 Toolbox SEN2COR 280 Processor and click Install. Navigate to Tools->Manage External Tools. Click edit Sen2Cor 280, in the Bundled binaries option. Selcet the right bundle for your operating system. Click the button to download and install sen2cor.