Hello Marisa,
When I downloaded Unite 8.2 2020-02-20 from this page, it initially showed me one file when I opened up the .gz file. Is this what you are seeing?
According to this post, that archive is actually a .tar.gz.
Once I renamed it, I was able to open it up and see the paired .fasta and .txt files inside.
Try renaming your file so it ends in .tar.gz and try extracting it again.
Let me know what you find!
Colin
P.S. Do we have any of the Unite devs on the forums? Maybe they can change their file names to avoid confusion.