No problem. Asking questions is all good! I'm glad you asked!
TWINDRILL is the doujin circle responsible for creating and distributing the various free resources attributed to the Kasane Teto character, including the UTAU voicebanks. It is a company, but a small group of a people (I think like 4 or 5) that have been working on the project mostly since its inception.
The character rights of Kasane Teto were adopted into the "Piapro characters" group through Crypton Future Media. This has resulted in character licensing creating official Kasane Teto merchandise and her inclusion in SEGA's Project DIVA games. Crypton Future Media has handled that licensing.
This is all to say that prior to Kasane Teto SV, all of the Kasane Teto works carried out by TWINDRILL were effectively on the level of "fan creations" even though they are official for Teto. Creating a product for SynthesizerV is a bit different.
AHS is a company that has developed and released VOCALOID, Voiceroid, and SynthesizerV products. A lot of these were independently produced and published by them. Others are solely published by them. In some cases, the products are developed by AHS *and* the supervision of another entity, such as in this case-- between AHS and TWINDRILL, for Kasane Teto. Another example of this would be the SynthesizerV version of Kyomachi Seika, which was produced between AHS and Seika Town.
We don't know the precise details, but it would be reasonable to guess that Crypton Future Media was responsible for establishing the relationship between AHS and Twindrill, or at the very least is collaborating on the business side of the logistics of licensing a character that they have partial stake in, from a legal perspective.