KB1906495: Google migration of the Google editor add-ons and related issues
Effective June 20, 2019, all Google Drive add-ons have been migrated from the Chrome Web Store to the G Suite Marketplace.
This migration of the add-ons from the Chrome Web Store was designed by Google to streamline editor add-on deployment and improve app discovery. The process has changed the look and feel of editor add-on management.
However, many users reported that the MarkdownTableMaker add-on was no longer available in the G Suite Marketplace, due to technical issues or administrative controls.
It is highly recommended that you contact your system administrator for details regarding installing and uninstalling Google editor add-ons.
Also, as mentioned in the Removal Guide (KB1907432), installing multiple instances of the same add-on has made uninstalling editors add-ons confusing for some users. The Removal Guide provides detailed steps to ensure complete removal.
Again, it is highly recommended that you contact your system administrator for details regarding installing and uninstalling Google editor add-ons.