I'm receiving an error message that only closing orders are allowed.
This indicates the contract month is within the expiration/delivery period. To trade the contract choose the next contract month.
If you get this error message when trying to enter an order, you need to add the next contract month for the product to your personal watchlist. In this case the contract is defaulting to the March 2025 expiration, but that contract is within the first notice day, delivery period, or close to expiration.
If you don't have a personal watchlist setup, click the watchlist name at the top of the window, click 'create new' and name the watchlist.
Start typing the symbol in the search bar, then click the futures tab:
Generally, choose the specific contract months on a quarterly expiration basis - March/June/Sept/Dec.
Check the CME Group website to see what contract months are 'lead' - https://www.cmegroup.com/markets/products.html#sortAsc.
Also, check the volume on the contract month chosen to make sure it looks correct.