"按合约方式" can be translated as "in accordance with the contractual terms" or "on a contractual basis".
"In accordance with the contractual terms" emphasizes following the specific stipulations outlined in the contract.
"On a contractual basis" highlights that the action or arrangement is carried out or established based on a contract.
Both expressions are commonly used in business and legal contexts to convey the idea of adhering to the terms of a contract.