Yes. You may add a referral code after registering a new account using the Fluz app's self-movement feature.
However, note that the self-movement feature only works if you do not have any invites or downlines under you yet. Once you have invited someone already, the self-movement function is not valid anymore.
Here's what you need to do:
Press the menu button (☰),
There will be a blue button that says "Add refer code" on the lower right. The button will only be there if this feature is still valid for your account. Otherwise, you cannot move under a referrer anymore.
Then enter your referrer's referral code.
if the referral link is http://joinfluz.app.link/EXAMPLE001, you only need to input "EXAMPLE001"
Once successful, you will immediately receive 3 vouchers for up to 35% cashback.