Depending on your role with Opus/Interfolio, there are several factors that may prevent you from uploading documents to a case.
When committee members find they cannot upload documents to a case, it is typically because they lack committee manager status. This can be addressed by contacting a department or school admin with committee manager or Interfolio administrator status and asking them to grant the status.
Before a candidate accesses their packet/dossier in Interfolio, an administrator must set up candidate requirements in order to require/allow the candidate to upload materials. Otherwise, they can only fill out forms.
There are two ways for an admin to allow a candidate to upload: by adding individual document requirements, or by enabling the options to add additional documents to a section. Both of these are set up on the Candidate Requirements page — more information is available in the articles linked below. Candidates who find they can’t upload should contact administrators in their department.
See Also
How to Upload Files as a Review Candidate
How to Upload Files as a Review Committee Member
What Is the Candidate Requirements Screen in Interfolio?
Where Can I Find The Documents in My Case?