Zoho One : Trial : Books and Inventory impossible to synch

Zoho One : Trial : Books and Inventory impossible to synch

Hello,

I'm trying Zoho One and want to enable Zoho Inventory Addon in Zoho Books.

I get this error message :

Oops! Looks like you have not subscribed to Zoho Inventory yet. Please upgrade your Inventory plan to use its features in Books.

Do I have to pay to test it ?

Thanks and regards