Hey nguyenbaokhanh,
Most of the new projects offering bounty explicitly mentions that you should not use ETH address of coinbase. To receive new coins, you should not use the ETH address for which you do not have private keys.

You can collect the coins only if you have full access of the wallet using private key. Coinbase doesn't provide the private key of your ETH wallet so you won't be able to collect your bounty coins on that.

You can create ETH wallet on sites such as MyEtherWallet or Metamask and use that address for bounty tokens.