"Not enough disk space"-Error while using diskexpander-Sketch

The problem is not the SD card, but the internal flash memory. In order to expand onto the SD card, some utilities must be installed to partition the SD card and then copy the required software to the card. The installer script is complaining that there is not enough internal flash memory to install those utilities.

You need to uninstall some previously installed utilities, or remove some of the larger files that you previously created on the internal flash storage.