The footprint size of the base is essentially the size of an iPad to give you a guide and reaches to 260mm/10.25" in height. When the iPad lays flat the height is 135mm/5.3".
The base is secured with concealed screws that are only accessible by unclipping the upper casing and rotating 90 degrees.
The tethering cable solution has a very versatile anchoring solution. Depending on whether you want this to be a permanent or temporary solution determines how the tether is secured. The optional anchor plate comes with a permanent and semi-permanent installation option.
Look in your kit for the security tab. Follow the instructions supplied within the kit for the security tab installation.