The parking lot is at the entrance area, at bottom right and called The Outpost on the map
https://www.wdwinfo.com/maps/FWMap.pdf. Guests who have reservations for Hoop Dee Doo Revue or activities such as horseback riding can park there and then take the internal bus to the relevant location. I think that guests can park without reservations if they want to visit, except for times like Halloween and Christmas when parking is more restricted.
My parents visited us two weeks ago (they were on the cabin resort reservation and we also had a Hoop De Doo reservation that night). Upon providing their magic band, for some reason, only the Hoop De Doo reservation pulled up at first, and they were told they were "too early" at ~2pm for the 6pm reservation and needed to come back later. The security CM was not going to let them park that early. Once they told them they were actually on the cabin reservation, and they verified that, they were allowed in, but at least on this day, they were not letting non-resort guests without reservations in to park in the front lot.
I also found it odd the Hoop de Doo reservation flagged before the resort reservation (you'd think it would be the reverse!)
Perhaps it was due to spring break, but they had definitely tightened things up and you definitely needed to be a guest or have a reservation to park that day - and be within a reasonable time of the reservation. I'm glad I added them, even though they were not actually sleeping in the cabin with us.
They had to park in the Outpost as we already had one car and a golf cart at our cabin site.
On another note, a cabin across from us attempted to park four cars in front of it. After a couple hours, I saw Disney security do a loop on their golf cart, notice it, and within ~30 mins or so, saw three of the four drivers leave. They are policing it, and I'm glad they did, as the extra cars had actually parked partially on the loop road, taking up about 1/3 of the lane.