Yes, you can. FTMO Futures is a separate product; the use of other FTMO products does not prevent you from using FTMO Futures.
Note that you use a single login for FTMO Futures and other FTMO products.
Since FTMO Futures are limited to clients registered as natural persons, contact our customer support if you are already registered as a self-employed person or legal entity. We will inform you about the possible solutions.