The ds2482 overlay does not appear to work on Raspbian Buster so you will have to enable the kernel module manually. The following steps should work.
sudo nano /etc/modules
Add the following to the end of the file:
Save the file and then edit /etc/rc.local
sudo nano /etc/rc.local
Add the following after the comments but before the exit 0 line:
echo ds2482 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
Save the file and reboot.
Your 1-wire devices should now be available in /sys/bus/w1/devices
Make sure you remove dtoverlay=ds2482 and dtoverlay=w1-gpio from /boot/config.txt otherwise it may not work correctly. I tried the steps above with a Raspberry Pi 4 and a clean install of the latest Raspbian linux and the two devices on my 1 Wire Pi Plus appear in the devices folder.