CESU and how it actually functions

I have taken on-board a Cleaner, through CESU. She cleans 2 hours each week, and as agreed with her, pay her 15€ per hour, that is 30€ per week. The first payment at end of November covered 3 weeks’ work, i.e. 6 hours, totalling 90€ which I paid her directly by my personal cheque. When I declared this amount on CESU website, I saw a net amount of 88 Euros that I should pay her, but I already paid her 90€, so I was OK with that.

I was shocked to find that CESU/URSSAF deducted, at the beginning of January 2021 from my personal account, an amount of 57€.  I do not know how this is could be as I thought there is no additional cost to me. This makes the total I pay on 6 hours of her work costing me 90+57= 147€, or 24.5€ /hr instead of Euros15€/hr !!

I have the following questions, so please clarify each for me to understand the system:
1. Do I pay the Cleaner’s social contributions? How are they calculated?
2. If I pay her social contributions, what is the benefit for me using CESU? What is the benefit to the Cleaner?
3. I hear about fiscal benefit to ‘Employer’, but what is the benefit if I am paying 9.5€ on top of the net of 15€ that I pay her?
4. How will I get my money back, OR, do I get my money back?
5. Is CESU a government set up of collecting more taxes, money money, from hard-earning people like me as an Auto-entrepreneur?
6. If there is a fiscal benefit, how do I claim it and how do I calculate it, and when do I get it?

This mechanics of CESU is very confusing. I count on you please to explain fully. Many thanks in advance.