Welcome to the Coinbase Cloud Developer Forum, @yefimg! We are always happy to help.
Upon checking the code snippet you provided, it looks like you were missing the client_order_id parameter which is a required parameter when placing an order. We suggest that you try running your code again, but this time, include the parameter client_order_id (unique uuid for this order ).
In addition to this, you may check this forum post which could be helpful with your case scenario. We highly suggest that you try looking into this for reference.
Please reply back to us if the issue still persists. Thank you and have a great day!