Glad you've got it sorted out!
By the bye, it's the EXE.XML file, not the EXE.DLL. Just want to be sure

The trick to that is be absolutely certain you have the path correct, to where YOUR copy of AICarriers is located on your HD. With FSX, it doesn't HAVE to be under your main FSX folder. That's something required by P3D. You certainly CAN put it there, but it's not a requirement, like with P3D. You just have to be accurate with the PATHING in your EXE.XML file. That includes capital letters, drive letters, etc etc. Finally, wherever you want AIC located, place ALL it's main folder, files, and subfolders there as well. You can't just have the .exe file in one location, and all the other fun stuff it needs someplace else.
There are many many carriers, not to mention other ships available for AIC, on many sites, like SOH, Simviation, Flightsim, and so on. Destroyers, cruisers, anything you can land a rotorcraft or fixed wing bird on.
A hint, when you begin adding, if I may: DON'T add the config files directly to the main AICarriers.cfg file. Go into the conf.d folder, and make a sub-folder in it, name of your choice. Place the new .cfg files THERE, and only place them into the conf.d folder when you might want to utilize them. If you add things directly into the main .cfg file, or the conf.d folder, you will wind up with so many pages to search through to find the ship you want when you hit SHFT-J, that it will take you longer to find your boat than to fly around it!
If you only place a .cfg file into the conf.d folder from your added sub-folder, it will keep your time searching through the SHFT+J menu reasonable. Copy the config file you want out of your new sub-folder into the conf.d folder, then when you want something different, delete it from the conf.d folder, and copy the new one in.
If you change the size of the main FSX window, BTW, shrinking it down, you will need to use your mouse to move down the menu pages available when you hit SHFT+J, or use your number pad to select the next page (9). When you shrink the FSX window, it tends to cut-off the bottom of the SHFT+J menu, so be aware.
There are some little tips and tricks to AIC, so be ready to have a bit of a learning curve.
Other than that, enjoy it! I sure do

Pat☺