All templates within are natively created in 1920x1080, but can easily be downsized within GenCG (Open file, then go to File -> Convert File Resolution).
Also, after downloading and extracting the zip file, the file format is GEF, which stands for "GenCG Embedded File". To open, go to File -> Import GEF in GenCG. Please note, GEF files do not include fonts.
If you have previous versions of GenCG, please first verify if your system is 5.5 capable before downloading: