Enable wifi on raspberry pi and connect to Apple TimeCapsule

wpa_supplicant.conf

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
network={
        ssid="moomin_wireless_network"
        proto=WPA2
        key_mgmt=WPA-PSK
        pairwise=TKIP CCMP
        group=TKIP CCMP
        psk=xxx
}

This got it done for me on a Raspberry Pi 3 B+

country=US
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
    ssid="NETWORK-NAME"
    psk="NETWORK-PASSWORD"
}