EE gave good advice...but 34" not 38"
It'll be 34" from where the string leaves the nut, to where the string leaves the saddle on the highest string, which on an EB5 is G string (and is also the thinnest).
If you measure from the 12th fret (the one with the double dots behind it) you measure from the center of the fret to the place where the string comes off of the saddle.
Here are a few diagrams to help with the parts of the instrument. I think you have a 5 string bass. The pics show a 4 string but it's basically the same.
You are correct that the manual assumes a minimum knowledge of guitar anatomy and maybe a little knowledge of tools and assembly techniques. However, the forum does not assume this, so keep asking your questions here! Most of us knew very little when we started... In my case I knew even less than I thought. You pick things up along the way ;-)
Note that what are called "Tuning pegs" below and "tuning head" or "machine heads" for some reason have many names. The can be called:
Tuners*
Tuning pegs
Tuning machines
Machine heads
Tuning heads
BTW, the "Headstock" can also be referred to as the "Peg head" or "tuning head"...but most frequently headstock.
What is called the "bridge bar" is more commonly called the "saddle" or "bridge saddle." It's bar shaped on most Fender basses, and I think on your IB5, more generically (and almost always on this forum) it is called a saddle.
I didn't find a better pic than the one above, but what they refer to as a "tone and volume controls" we would refer to on the form as "tone and volume potentiometers" (or pots for short).
Hope this helps!