A lot of christians find the imagery in zoroastrianism to look 'satanic', so a lot of edgetard satanists latched onto it.
That's about it.
In addition, Ahriman, their supposed god, is the spirit of evil and corruption in Zoroastrianism and has a lot of thematic parallels to the common Christian perception of Satan. That's why they call their church a dakhma, or "tower of silence", because Zoroastrians believe dead bodies to be a corrupting influence, they place them in a tower open to the sky to be eaten by carrion birds. The dead bodies, obviously, are considered associated with Ahriman.