Pricing of zephyr scale

Hi There, 

I have a pricing issue for zephyr scale, as far as i know the pricing is free if the member of zephyr scale less than 10 members,

In my current office we used jira conventional with 22 members and I tried integrating that jira with zephyr scale with permission to access only 1 member to zephyr scale, however due to we used convectional jira with 22 member after 3 months there's billing invoice from  zephyr scale. my questions : 

1. for this case, are we not eligible to get free access zephyr scale ?

2. if eligible , could help me to guide how to config it ? 

Thanks  in advance