Okay, I assume I delete the ones named EXACTLY that, but what is the optional one?
I guess I am misunderstanding your question. In the Hiver Swarm main folder look for and open a txt file named README that has all the locations of the optional files and how to enable them. I hope that helps, if not let me know.
I'm asking what the OPTIONAL files are called originally, cause I'm not sure which one I am meant to modify.
The mod comes with several different options which are detailed in the README. Your original question was on how to make their "stuff" purchasable. Keep in mind that first the only way you can buy their assets would be to go through the arms dealer when you enable that option. By default they are hostile to all and you would be unable to just dock on one of their planets and buy things like a normal faction.
All the optional features have to be done manually by you, there is no in game menu. Navigate to w/e drive and folder you installed Starsector, there will be a subfolder called "mods". In that subfolder look for a subfolder called "Hiver Swarm 1.08c". Now in that subfolder is the directions, data and graphic files pertaining to Hiver Swarm.
The location of the instructions on how to enable those optional features are detailed in the file called "README" which is located in Starsector\mods\Hiver Swarm 1.08c and it can be opened with any text editor like notepad, Word, etc. If for some reason you do not have a text editor, I also have the instruction located on the Hiver Forum main page,
https://fractalsoftworks.com/forum/index.php?topic=22965.0 now look for a bolded line "The mod comes with several optional files that can be enabled before the start of a new game - below that are the various instructions on how to enable the various optional files under spoiler tags.
To enable ships to be purchasable via the arms dealer, navigate to: Starsector\mods\Hiver Swarm 1.08c\data\hulls and follow the directions in the README
To enable weapons to be purchasable via the arms dealer, navigate to: Starsector\mods\Hiver Swarm 1.08c\data\weapons and follow the directions in the README