Please don't worry about the wording of this document, you are not obligated to pay me at all.
This is just the (contract) documentation that you actually don't have to worry about at all.
Please don't worry too much about what it says. This is just the paper work that we never follow anyway.
"This document is to guarantee that you will be paid for the agreed amount of wage." ＝「合意したぶんの給料支払いがなされることをこの文書が保証します」
支払いの義務がない、は"you are not obligated to pay (make the payment)"です。「義務」＝"obligation", "mandatories" 。簡単に伝えるには、"Don't worry about this document too much, because we are not asking you to pay. It is just a part of the paperwork and we can ignore it." 「書類だから無視していいんだけど、実際に支払って欲しい訳ではないから、（＝書類に強制力がないことを示唆して）心配しないでね」とはっきり言われるといいです。
日本 
