According to the Trust Wallet support page, one's account needs to reserve at least 20 XRP in the shared global ledger before transactions can go through. It is a requirement. A minimum of 20XRP is needed for the network functionality. So once you finance you Ripple wallet address with 20 XRP or more, your account will become active and usable. This is a one-time necessity, specifically for new address, which you generally need to keep up.