Before you are assigned an LTC address, you need to enable a Litecoin wallet on your account.
You can do this via the Settings -> My Wallets page.
Simply tap the '+' symbol next to LTC, and tap "Confirm" to permanently enable it on your account.
Note: it is not possible to connect the LTC wallet to the TenX Card. At the moment, only BTC and ETH wallets can be linked to the TenX Card.