The Koha Offline Scanner‘s purpose is to support your library circulation process while your Koha system is not accessible for any reason.
It runs on your iPhone, which has its own battery and its own internal barcode scanner (the camera), and is therefore also independent of power.
The tool has at no time a connection to your Koha system, and has therefore no information about your patrons and books - you only deal with barcodes.
After your offline work is done, simply share the result with your Koha librarian or administrator, who can upload your offline work into Koha, as soon your Koha system is back available.