I’ve finally fixed my issue, as @EOD_Trader said in his post…
https://community.tradovate.com/t/401-access-denied-in-order-placeorder/3650/8
When using the real account, it seems to be mandatory to include the deviceId field in the login credentials if orders are to be placed.
Later I found that the deviceId can be directly located in the Tradovate platform, when clicking Curl in the API keys configuration.
Thanks for your support.