Please make sure that the resume files are compressed to zip only. To zip the resume files, use Window achiever (Like Winrar or Winzip) only and make sure you will select all files and compress them, not a folder. I am afraid that indexing might not work with other compression tools. Now, upload the Zip file to the portal (Bulk or single resume/JD).
You can contact the RChilli Support team via creating a ticket at RChilli HelpDesk or you can send an email at firstname.lastname@example.org for any kind of assistance.