GCD 7.0 is still in pre-release mode. If you're looking for a stable version please download GCD 6.0:
Latest stable release of GCD 6: GCD 6.1.14
The GCD 7 software is now available in two different flavors. The GCD Addin for ArcGIS provides full GCD functionality, including map display of GCD inputs and outputs. If you have ArcGIS 10.4 or newer (not ArcPro) then this version will give you ‘Add to Map’ and spatial visualization functionality embedded within ArcGIS. The downside is ArcGIS is a 32 Bit Application and can only use 4 GB of RAM, so it is slower.
GCD Standalone is a desktop software version that performs all the core GCD functionality (building projects and perfoming change detection analyses etc) but does not include any map display. If you don’t possess ArcGIS, or you want to use an alternative map display tool, such as QGIS, then we recommend this version. It also works as a nice companion to the Add-In and you can go back and forth between the Add-In and Stand-Alone seamlessly. Note that GCD performs all spatial operations using the free and open source GDAL library. Therefore you do not need ArcGIS to use GCD Standalone.