Hi Nathiel,
Thanks for using Super RSS Reader.
I believe the downloaded ZIP file is corrupted. Can you please check if you can extract/open the zip file you downloaded on your PC ?
If not please do try downloading again.
If you are able to extract the file but if issue happens only after uploading, then possibly some space issue in your server to extract the files.
Other way is to extract the folder and use FTP to upload the folder as a whole.
If issue persists, please email me the zip file to aakash.19493 [at] gmail.com for my analysis.
It does seem pretty common please do see if any of the results below help.
https://www.google.com/search?q=PCLZIP_ERR_BAD_FORMAT
Thanks,
Aakash