Currently, deposits on the platform are executed using smart contracts. Even though it is a more secure solution, some exchanges and wallet services (e.g. Bitfinex, Binance, KuCoin, OKEx, blockchain.info) don't support transactions to smart contract addresses.
We seek to implement a more comfortable solution shortly, with new addresses which support transfers from a wider range of exchanges and wallet services.
Until then we recommend to use a local wallet. You can deposit your funds from exchange and wallet service into it and then transfer them into your Covesting wallet.