The alignment kit is a set of bolts that replace the stock bolts that attach the strut to the knuckle. The Eibach camber bolts are a smaller diameter than the stock bolts and have a lobe on them just like a cam shaft would that allows you to rotate the bolt to increase or decrease the camber on the front wheels. This is only needed when droping the car alot. I have my car lowered 2" on coilovers and still didn't need the camber bolts. I was able to get the alignment where I wanted it but that was all of the adjustment left. So if I wanted to dial in more toe for auto-x then I would need to use the camber bolts.
I had the Eibach Sportline kit (for a 03+ Tiburon) installed on my 04 Elantra, and now the car drifts right and the steering wheel is about 5 degrees counter clockwise. Tomorrow I have a wheel alignment appointment with a shop here that works on lowered cars... So I dont know yet if I only need an alignment or if I also need a camber kit. Something is off for sure.
You won't need an alignment kit. It's just that your camber & toe settings are uneven. The struts have some slack at the knuckles so whenever you unbolt the suspension and put it back together, it's never in the same position it was. The alignment shop can fix that without a kit. Your car will have more negative camber than it did, but it'll probably still be within specs.