How do "matching deductions" work?

• The ADHA discounts your national dues by 25%
• onDiem splits the rest with you, which means they’ll pay for 50% of your remaining dues.
• Your remaining dues will be paid in 4 equal installments over 4 completed onDiem shifts (6+ hours). For each installment, onDiem will deduct half from your paycheck, and match and pay the other half. 
• Once you’ve completed 4 shifts, you’ll be a fully paid member of the ADHA for the remainder of the annual term.