Because it is a manual transmission, they most likely disabled the remote start feature. There are multiple additional connections to make in order for it to work properly and safely. I agree with everyone here... pay a professional.
Morse: 8 hours ?!?!?!?! I own my own install business and have already done probably 4 or 5 new wrx's this season... and none of them took me over 3 hours. And even the 3 hour install was a full alarm with multiple sensors and additional options... and the first one I did. The last one I did (just a basic remote start / keyless entry) was done in about 1.5 hours.