RSI should be sending demands in respect of your business income. You would have had to have declared how often you wished these demands to be. Mine are every three months. I became registered with them last June. I have not yet got any income, so I declare zero. However Every time I go to the hospital or doctor it is RSI that pays that portion which was previously paid by CPAM. I am not an inactive, but a British pensioner, and had S1 working for me before.
You must find out where your RSI office is, and which organisation you chose to operate the RSI. I had a choice of several, and I chose UMCAPI, There was no special reason for the choice.
My whole business was set up during a meeting with the local Chamber of Commerce, and I would suggest that you make an appointment with them, and sort everything out.
Had you been registered as a Professional LIberal, you would have been paying cotisations to URSSAF despite having no income from the business.