"To tap an amiibo" means to place an amiibo figure or card on a gaming device in order to interact with it or unlock special content in the game. Full definition
It has spaces for stamps of each compatible amiibo that can be obtained by tapping their amiibo figure, and will give you rewards as you fill it out. (monamiibo.com)
By tapping amiibo into the game, you will receive a chest with a series of items. (eurogamer.net)
Imagine something similar in Animal Crossing where tapping an amiibo card could yield you items. (brokenjoysticks.net)