Sure your disk has enouth space. Be careful! Frequent writes to disk may may damage it. Speed depends on your machine and network connection. Read my comments -- incorrect params due initialization may cause some problems. I don't have tested it on *nix.
First you need get access_token for you. Create your own standalone app at https://vk.com/editapp?act=create. Then read https://vk.com/dev/implicit_flow_user. Or you can use my app, go to https://oauth.vk.com/authorize?client_id=7413734&display=page&scope=friends,photos,groups,offline&response_type=code&v=5.103.