Zip won't extract

Hi,

I am trying to insert a theme I bought for word press, however, after I’ve uploaded it to my file manager in cPanel I then try to extract it and this is the error message that comes up:

Archive: /home/srahmh/public_html/wp-content/themes/swell.zip
End-of-central-directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi-part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of /home/srahmh/public_html/wp-content/themes/swell.zip or
/home/srahmh/public_html/wp-content/themes/swell.zip.zip, and cannot find /home/srahmh/public_html/wp-content/themes/swell.zip.ZIP, period.

Not sure what this means. I have tried deleting and re-downloading. Nothing works. I’m pretty lost here. Would appreciate some guidance!

Cheers