Biometric Residence Permit (BRP) for EEA citizens

[steca-stef]

Hello,
I am an Italian citizen applying for British citizenship with an ILR.

I have a question about biometric data. The citizenship application form asks:

Do you have a Biometric Residence Permit (BRP)?

I have never had a BRP and answered "No" to this question.
I remember reading somewhere, but I don't remember where, that it is not mandatory for EU citizens.

Do I need to book an appointment if the BRP is mandatory?
Can I book it after I've made the payment?

Thanks in advance
S.