The Vigor 2762 has two USB ports which can be used for 3G/4G modems, USB storage, or a printer for shared access.
You can connect a USB 3G/4G modem to the Vigor2762 and use the cellular networks (EE, O2, BT, Vodafone, Virgin, Three) as your Internet connectivity. That can be your primary (only) connection, or the router can switch over to 4G in the case of ADSL/VDSL outage so that you're always connected.
You can use your Vigor 2762 as a network attached storage (NAS) with Windows networking (SMB) & FTP connectivity, to allow Windows, Apple, Android and Linux devices to easily access the router's storage.
You can also let users upload files - each storage user account can have their own login and read-only or read-write FTP access to a preset directory.