For WPS Push Button method,after the ESP32 boots up and prints that WPS has started, press the button that looks something like this on your router. In case you dont find anything similar, check your router specs if it does really support WPS Push functionality.
As for WPS Pin Mode, it will output a 8 digit Pin on the Serial Monitor that will change every 2 minutes if it hasn't connected. You need to log in to your router (generally reaching 192.168.0.1) and enter the pin shown in Serial Monitor in the WPS Settings of your router.
ets Jun 8 2016 00:22:57
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0010,len:4
load:0x3fff0014,len:732
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a14
Starting WPS
Station Mode Started
WPS Timedout, retrying
WPS Timedout, retrying
ets Jun 8 2016 00:22:57
rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
ets Jun 8 2016 00:22:57
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0010,len:4
load:0x3fff0014,len:732
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a14
Starting WPS
Station Mode Started
WPS Successful, stopping WPS and connecting to: < Your Router SSID >
Disconnected from station, attempting reconnection
Connected to : < Your Router SSID >
Got IP: 192.168.1.100
ets Jun 8 2016 00:22:57
rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
ets Jun 8 2016 00:22:57
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0010,len:4
load:0x3fff0014,len:732
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a14
Starting WPS
Station Mode Started
WPS_PIN = 94842104
WPS Timedout, retrying
WPS_PIN = 55814171
WPS Timedout, retrying
WPS_PIN = 71321622
ets Jun 8 2016 00:22:57
rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0xee
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:DIO, clock div:1
load:0x3fff0010,len:4
load:0x3fff0014,len:732
load:0x40078000,len:0
load:0x40078000,len:11572
entry 0x40078a14
Starting WPS
Station Mode Started
WPS_PIN = 36807581
WPS Successful, stopping WPS and connecting to: <Your Router SSID>
Disconnected from station, attempting reconnection
Connected to :<Your Router SSID>
Got IP: 192.168.1.100