The key phrase here is "Indulgence not compulsion". You must study these tenets as if they are commandments. Then apply them religiously. Sea horses.
It is worth noting that if it is in an area (state, country, or municipality) that allows for its legal use it is ok. Satanists are law abiding after all.
Most importantly, it must be cosigned by authority first.
Fun Fact: The super fundamentalist Christian subgroup called Rastafarians consider ganja sacramental. It grew from some dead ethiopian king's (because they were all kings) grave so they consider it their prophet's final gift, allegedly. They also listen to the verse in Leviticus that says you don't ever cut your hair, as opposed to the other one in Deuteronomy that says you should cut your hair.
again, I am fairly new to the scene. I was a tad confused because if I am my own god, then why can I not make my own rules. But there seemed to be a strong disdain for substance use.
It only says this in the contexts of Satanic Sex and Sacrifice.
Assuming we take Lavey's Satanism to be the authoritative source regarding what Satanism is, it should be noted that LaVey's Satanism was, and in many ways still is, a counter-point to all things hippy and new-age. The tone of the The Satanic Witch is especially derisive of the very notion of chemically induced consciousness expansion - a topic mentioned briefly in the Satanic Bible.
Eisegesis of the Satanic Bible aside, the stance of the C/S (Church of Satan) in regards to cannabis use can be found here: https://www.churchofsatan.com/policy-on-drug-abuse.php It unequivocally condemns it precisely because it has nothing at all to gain and everything to lose by condoning it. As your own god, it is implied that you are capable of making your own decisions and are free to ignore the advice of others at your own peril.
Of course, I still have to question exactly how satanic a person can really be who needs the approval of a higher authority to determine what is and is not acceptable to indulge in.