This article provides information on how to set up a network share that is usable and secure.
Follow the process detailed in Microsoft's article to share a folder for network use. You need proper access to the server to set the permissions. Therefore, you need Domain Admin rights. Please keep in mind that folder sharing settings and permissions for both Share and NTFS should be set according to your company's security policy.
Once the folder is ready to be shared, make sure the FaxMaker service account has write access to the shared folder. To verify this, check the FaxMaker service accounts that are in use to add the permissions. This account should be added with write access to the shared folder for FaxMaker to be able to deposit files there.
Once FaxMaker is set up to back up faxes to a folder or share, test it with an inbound fax to the appropriate number.