Absolutely. You can either upload your files directly into a project, OR email your account address (e.g. yourtenantname@workguru.email) and put the project number in the subject line, and the email and any files will be attached to the project automatically. Note: WorkGuru has a file size limit of 10MB.
You can also integration WorkGuru to cloud based file storage such as Google Drive, Dropbox or Suitefiles.