It might not be that you are doing something wrong, as there were issues with the main extension repository (i.e. ibiblio.org). They might be still ongoing, but I'm not sure since I have my own private mirror for the stuff I'm interested in.
To get a better idea about the type of error messages I'd suggest you run tce-load -wi compiletc in a shell. This might reveal some more details and is exactly what gets executed "in the backend" when you attempted the installation via 'appbrowser'.