Documents uploaded to the site are searchable if they are machine-readable and not scanned.
Ways you can upload documents to be searchable:
Upload a Word document and convert it to a PDF.
Create a document in Word and save it as a PDF, then upload.
Create a document in Adobe Acrobat Pro and save it as a PDF, then upload.
Important Note:
Scanned documents are not searchable nor are they acceptable for accessibility standards. They should not be uploaded to the site if possible.