Both creators and downloaders need to link to their subscription sites, like Patreon. This is because creators often release different content to specific tiers. We'll need to be able to see what tiers your account is subscribed to, in order to grant access to download those restricted files.
You won't even need to be logged in, or have a subscription site linked, to download an unrestricted file. Although, for these unrestricted files, we can't identify downloaders.
We treat all data you share with us as confidential. We don't sell your details, and we don't share information with anyone. We will only share your ID for a subscription site, to those you have already subscribed to (e.g. to the Creator Patreon for someone you are a Patron of). They will already have this information on that site.
On Patreon's Settings page for Apps, there should be a section for apps logged into patreon. FileID should be listed there, and you can disconnect it. By doing so, FileID can no longer grant you access to downloads from creators you have subscribed to, as we won't be able to know if you're still eligible.
If you've pledged to FileID on Patreon, you should have a link on your dashboard to analyse a file. Using this tool will be able to reveal the original downloader, if this file came from here. We can't do this if they downloaded the file from a different file host.
That's up to you. If we've identified someone, we're certain of that result. This doesn't mean they were the person to have shared your content to a wider audience, it only means they shared your content to someone. It may be those they shared it with, uploaded it to the wider audience.