As noted in section 5 of the terms and conditions, images on Unsplash come with a very, very broad copyright license under the Unsplash License. This is why we say that they are “Free to Use.”
Note that the Unsplash License does not include the right to use:
Trademarks, logos, or brands visible in an image
Recognizable people in an image
Works of art or other copyrighted material depicted in an image
If you download images with any of these depicted in them, you may need the permission of the brand owner of the brand, or the work of authorship, or the individual, depending on how you use the Image.
In general, if you're using the images for non-commercial purposes, in positive contexts, and you're not implying an endorsement from the trademark holder, then you can likely use the images. If you are unsure or have any questions, we suggest consulting with a lawyer.