If they have a condition before you can get that $100, then it is not similar to MetaWin since it's called a "giveaway." You don't put conditions on that to withdraw the funds. It should have simple rules just like what is stated in the post, and then the random winner will get a free $100 credited to their account, probably.
You’re right, typically casino giveaways rewards comes with a rollover requirements before you can withdraw and most of the time it’s an insane rollover requirements that makes it hard to complete.
It’s very rare for me to see this same giveaway on social media without any requirements since casino usually stricter in there due to the possibility of multiple account abuse. Only on the casino game and rounds giveaways has same mechanics with Metawin promotion but most competitors on X has an insane requirements hidden on the promotion ToS.