The Finom card you will receive will automatically be equipped with the contactless payment option, and you can use it as soon as your card has been activated.
If you want to know how to activate the card read this dedicated article.
At the moment there is no option to disable contactless payment, however, as paying by contactless is not mandatory, you can choose when to pay by contactless, or by chip & PIN, according to your needs.
Contactless payments for amounts over 50 Euro require a confirmation via PIN code. If you need more information about Finom card's PIN code, read the article at this link.