FS Rd 1576 crosses Mill Creek just upstream from the MTNF picnic area, and follows a different creek/hollow, up a ridge to cross Hwy T, then down the other side to the Vida Slab Bridge on the Little Piney. The road it branches off from runs from Hwy P, along Mill, past the Picnic area, and then to Bohigian on Hwy AA.
So basically, those red marks are for parking along Kaintuck Hollow, and not Mill Creek. If you come from Newburg, take T to P, you'll see the MTNF Mill Creek Picnic area sign on the right, with the gravel road on the left. Go a couple miles and the parking area will be on your left. Or, you could pass this road, go up the hill, take the left on AA, and then Bohigian will be on your left. Gravel parking lot.