With your iPhone:
Open the Wallet app on your iPhone
Tap Add or the plus sign and follow the instructions
With your Apple Watch:
Open the Apple Watch app on your iPhone
Tap on "Wallet & Apple Pay" and select "Add credit or debit card"
Enter the security code of your Clanq card to add the card that is linked to your Apple account
It takes 24 h from the card issuance, before it can be added to the Apple Pay.