"This shared file or folder link has been removed or is unavailable to you."

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.

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 permissions or to send you the correct link to the file.

To learn more about Shared link and setting correct permissions, please take a look at this article: https://support.box.com/hc/en-us/articles/360043697094-Creating-Shared-Links 

Best Regards,