From their logo guide, I am assuming the answer is yes, though I would contact for clarity in regards to how they may be used.
From their logo guide, the following text outlines such usage, but isn’t clear as to any limitations:
If you’re creating materials—i.e. business cards, banner taglines, flyers, letterheads, etc.—or other collateral that is representative of the DO brand, we recommend using the font Sailec.
With emphasis on:
Use the DO logos as provided and
please do not make any changes to them. :)
You can review the logo guidelines here:
The above text is number 11 on the list.