The driver packet is handed out at the rally starting point. But keep an eye on the rally information page regularly so you will know where the overnight stops are located.
I'm unusual (ya think?) in that I have taken my daily driver on the rallies. I'm not even in it for points or for winning it--I like road trips anyway, and having an event that is equal parts interesting/obscure history, scavenger hunt, camaraderie, and visiting places I most likely have never visited, let alone heard of, makes it worthwhile. I'm already signed up (and have rooms reserved for) Rocky Mtn Breakdown, and am taking the daily driver/road trip vehicle since I have other travel plans and work commitments before and after where I'll need it.
I did my most chancy rally so far in taking a car (#EarlBurnerCivic) I had just finished replacing the piston rings and honing the cylinders in, just a month before the rally with nothing more than running short errands locally as a shake down. But it performed mostly without a hitch. (I got a tree branch wedged between the tire and suspension on the first night, and it did a German Car Thing™ with the check engine light taunting me for a P0420 error).
For Rust Belt this year, I might have a "revival" of a vehicle that's been sitting here mostly undriven since 2016 that I either need to scrap or part out, or get running long enough for the rally, provided it is not so badly rusted that it is unsafe (which I think it may be). If not, the spare car will be used (Earl Burner), or I may convince my youngest to use her TSX as I have a car theme that would work perfectly on black paint.
Everyone does rallies in their own way, so as others have said, something street legal that won't take a dump the moment you pull out of the driveway will work, as will a rental. In my case, funds are limited, so I drive what I can. Gas and hotel rooms aren't inexpensive anymore. Add the rally fees and the days of lost productivity (I work for myself--no work = no money), and I can't be dumping it into a money pit crap can. Not that I've ever stopped looking for a project car, especially one that Eric and Jeff thought might be cool for a rally...
Driver of soul-sucking appliances in the Rust Belt.