The KEPServerEX ThingWorx Native Interface was originally released with KEPServerEX v5.21 to enable connectivity with v6.6 of the ThingWorx Platform. Compatibility with the ThingWorx NextGen Composer (v7.4) was implemented with the release of KEPServerEX v6.1, while still allowing support of older ThingWorx composer versions through the Native Interface "Legacy mode" setting.
When connecting with ThingWorx v7.4 and newer, an Industrial Gateway thing template is configured in the NextGen Composer. The instructions for connecting KEPServerEX v6.1 (and newer) with ThingWorx v7.4 (and newer) can be found in the ThingWorx Help Center here:
When connecting with versions of ThingWorx that are older than v7.4-- or if the older version of ThingWorx composer will be used-- it will necessary to download and import the KEPServerEX Extension from the ThingWorx marketplace. The "RemoteKEPServerEXThing" thing template will then be used to allow connection with KEPServerEX. Here is a link to the extension download: