No land to start on Agrarian Skies?

After looking around a bit, there appear to be two possible reasons for that.

Firstly, selecting a new world does not work, since the skyblock is not generated like that. If you don't have a savegame already for some reason, you can download the map here. Put it in your saves directory inside your directory for AS, launch the game and select that world.

If you use that savegame and still spawn in the void, here's a quote by jadedcat herself:

If you spawn and fall through the void swap to creative and fly up. Use /jspawn set to set the spawn to the platform.

The easier way, on the Maps & Textures tab of the FTB Launcher are the maps available to download. By selecting your Agrarian Skies mod pack in the bottom pulldown (next to the Install button), it will install the maps for you. FYI, you may have to click the Maps button on the top as it seems to default the Texture Packs list.

Thanks to everyone who tried to help me out here! I seem to have found out the answer on my own though.

As far as whether or not the blank world on spawn is intentional, I do believe that it is. The intention is that you will go and download the world file form this Curseforge link uploaded by Jadedcat, and put it in your saves folder (roughly under the AgrarianSkiesHQ folder, then the minecraft folder in there, unless you changed it at all.

As to where this folder is, it really depends on where you put your FTB folder when you downloaded the FTB launcher and ran it for the first time). The one that I was looking for (and mostly likely the one any singleplayer would want) was the "Home.zip" download.

This is the map with a barn and what-not, the one that was showcased on the Minecraft Forum blog for a bit. After this, unzip the file (it has been a bit, but I believe that you need to unzip it) in the saves folder, delete the zip if you so choose, launch AgSkies, and select the newly included map. Voila! There is land!

This worked for me, but I will see if it works for others before I mark the question as answered.