This error typically is caused by one of 3 things:
  1. Incorrect sharing permissions on the shared file. In other words, whoever created the link did not set the correct access level on the link. If you are not already a collaborator in the folder (or file) the link points to, the link would need to be set to "people in the company" (if that person is also at your company) or "people with the link" (if that person is not part of your company).
  2. The person who created the shared link has since removed it.
  3. You are attempting to access the shared file with a personal Box account instead of the account with which the file was shared.
Here's what you can do:
  1. Verify you are logging into Box with the account to which the file was shared. Typically this will be your company Box account.
  2. If that doesn't resolve the issue, contact the individual who owns the file. Ask them to either to review and revise the file share permisions or to send you the correct link to the file.
  3. If that doesn't resolve the issue, contact your organization's IT admin for help locating the file and fixing the permissions.

In addition to this, to confirm if the invitation was sent to your Box account. Please do the following steps to accept your pending invitation. 

To find and resolve a pending invitation:

  1. In the left menu of your Box account window, click All Files.
  2. In the pending invitations panel under ACTION REQUIRED, hover on the name of a file or folder.
  3. To see details about the invitation, click the ellipses, "...", and select View Details.
  4. To accept the invitation and gain access to the project's content, click Accept.

If you can't find it, please reach out to the folder owner and have the user to send you a new invitation. 

Hope it helps!