To find out as what USB device the ESP32 is connected, open Terminal and enter:
ls /dev/tty* | grep usb
in my case I got
/dev/tty.usbserial-14120
Now we can connect via screen:
screen /dev/tty.usbserial-14120 115200
When you reset the board you should see something like this
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:2
load:0x3fff0030,len:5656
load:0x40078000,len:12696
load:0x40080400,len:4292
entry 0x400806b0
To end the session in screen, press Ctrl+a, and type :quit and press Enter.
Further Reading
Using MicroPython on FireBeetle ESP32