UPDATES ARE BROKEN - NEED LINK FOR CORE PLUGIN (DOWNLOAD) ?

we pay for the pro plugin and have no access to the core plugin required for functionality? please help me understand - updates to core are broken and i need to upload from a local folder - please supply the link for the additional plugin required to make this work.... as we are now paying a premium for product and service .... please cover the basics.... kai
(multisite functionality was not built into the product (and no real part of the roadmap) ? thanks, will try another way....