It's pretty much keep it to your FC only. You can't take it into the public hubs or any public chats or party finder. It doesn't matter if it's for something harmless like cancer awareness, it has nothing to do with the game and therefore isn't allowed in public spaces.
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Source from the ToS if you click Key Points under the section referenced in OP's post.
It is prohibited to engage in activities or advertisements in public areas where many players can see them, such as Shout and through the Party Finder. If a report has been filed and the prohibited activity is confirmed, a penalty will be issued.
In a closed environment within a private chat such as a Linkshell or Free Company, it is not considered a violation to raise such topics among peers, but if the conversation is repeated persistently, please be aware that it may be considered a violation depending on the circumstances.
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It's also pretty defined what is prohibited:
refer to the act of engaging in activities and promotions that involve real-life political groups, religious organizations, or business entities that have no connections to Final Fantasy XIV. Even if the activity is for charity, it is prohibited as the activity is not relevant to the game.
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So therefore, if you want to raise awareness for something or collect donations for charity, it has to be within your FC or friend group. Anything else is a violation and will get you penalized if someone reports it.
As far as what grounds a violation in private chats, most likely if you annoy your friends with talking about your cause non-stop and they report it you can get penalized.
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TLDR: You can't raise awareness or collect donations for a charity or other charitable cause in public spaces, keep to your friend group or FC. Be aware that if you annoy them with talking about it that it can get you penalized. Do all charitable work on Discord to save yourself a headache.