We do not recommend trying to do this if you are not familiar with using unix command line. You can get in a mess very quickly.
In the following example the disk path name /Volumes/HDD/VelociDrone is a made up path name just to use as an example - you need to use your own valid path to your own hard drive - you cannot just type these command in verbatim, you must insert a valid path relevant for your own system.
1. Make an empty directory on your bigger volume (for instance mkdir /Volumes/HDD/VelociDrone)
2. Make sure that you have write permissions to that directory (chown it if necessary)
3. Execute:
rm -rf ~/Library/Application\ Support/PatchKit/Apps/32bc8fc6
ln -s /Volumes/HDD/VelociDrone ~/Library/Application\ Support/PatchKit/Apps/32bc8fc6
On some machines you may need to only move the data directory as OSX won't run ther application if the root executables are not on the system drive (which seems to be a new OSX requirement). So this would be the command to use instead ...
ln -s /Volumes/HDD/VelociDrone ~/Library/Application\ Support/PatchKit/Apps/32bc8fc6/Data
Now run the launcher. Game will be installed on your bigger volume and it should no longer complain about the disk space if your usual drive is lacking space.
NOTE: For M1/M2/M3/Mx clients the 32bc8fc6 should be replaced with 90b8d122