These are various files created by other talented modders.
From the author's readme:
Designed to take on smaller enemy capital ships when an Imperial cruiser is unavailable, the TIE Archer was one of the Empire’s more successful answers to the New Republic’s B-wing heavy bomber. The Archer is heavily armed, lightning fast and is equipped with both a shield system and a hyperdrive. Of course, such performance comes at a cost. The Archer is extremely expensive to build and maintain, and uses parts that are not common among other TIE variants. Most fleets can only afford to keep a single squadron of Archers running at any one time. The Archer is also notoriously difficult to handle and is usually reserved only for those pilots who have survived a tour of duty in both the TIE Interceptor and TIE Defender, or who show an inherent aptitude for combat. Unlike most TIEs in the Imperial fleet, the Archer is a two-man fighter with a pilot and a navigational officer seated in separate pods within the Archer’s elongated cockpit. In an emergency, however, the Archer can be operated by a single pilot. The large solar panel to the rear of the cockpit appends those on the wings, allowing the collection of more usable solar energy needed to produce the Archer’s high performance rating.
Unfortunately, due to its age and not being updated, this shipset is no longer compatible with the game in its current state. Apparently some OPTs required by the campaign are no longer available and as such will cause the game to crash upon mission load.