All measurements you provide in the form are finished measurements for the sweater, not your body measurements.
If you want a close-fitting sweater with zero ease, then input your body measurements. If you want 10cm/5" of
positive ease in the body, then add 10cm/5" to the chest size, etc.
Even if you're designing a close-fitting sweater, you probably want at least a little bit of positive ease
around the top of the sleeve. The cast-on edge that occurs at the armpit doesn't stretch as much as the rest of the
knit fabric, so a sleeve with zero or negative ease at the upper arm can easily feel tight, even if the rest
of the sweater feels fine with zero/negative ease.
The sleeve length that you specify will be the length down to the end of the ribbing, and instructions will
be included for 5cm/2" of ribbing within that length.
Similarly the overall body length that you specify is the length down to the bottom of the ribbing, and the
instructions will include 5cm/2" of ribbing at the hem.
Instructions will be included for 3cm/2¼" of ribbing at the neckline. Since that ribbing draws the
neck opening in somewhat, the final neck size can be a little smaller than the size you see specified here.
If you think that will be too small, you can use the custom crew neck size feature to increase it a little,
or you can finish the neck a different way (eg an applied i-cord edge).