As long as you know the login details for the Google account on it, you can reset it yourself.
Start with the phone turned off. Press and hold the Power and Volume Down buttons simultaneously. Hold until the screen starts. You’ll enter Recovery Mode. You can now use the volume buttons to navigate and the power button to select. Hit the Volume Down button until you highlight Wipe data/factory reset. Press the Power button to select the option. Confirm by selecting Factory data reset and let the phone do its thing. Select Reboot system now.
(Copied that off a website so the formatting is a lil odd)
Most features from find unlock was removed so best bet is to contact customer service with proof of purchase.
You Can do under support section in members app under support section "contact us" give customer service a call or best bet would be visit samsung experience store.