MATE is a great desktop and seems to be very stable and quick with FreeBSD. Follow the link below on setting it up, this person gives a good basic tutorial.
A more in depth install is covered here… https://cooltrainer.org/a-freebsd-desktop-howto/
If you want to get Slim to auto login, you can do that be editing the slim conf file…
# ee /usr/local/etc/slim.conf
down towards the end, uncomment the “default_user” field and to the right, put your default user name. Then just below that, uncomment auto_login and set it to “yes”.
I also wanted to get Remote Desktop working so I could VNC into my box. X11vnc is the best for this. It will use the current display.
# pkg install x11vnc
# x11vnc -storepasswd (then put your password in, it will put it in a file .vnc/passwd)
# ee vnc.sh (create a script to enable VNC server to listen and stay on even after you disconnect)
#!/usr/local/bin/bash or ( #!/bin/sh if you are using default shell )
x11vnc -rfbauth ~/.vnc/passwd -forever -display :0 &
##### exit and save the file.
# chmod a+x vnc.sh
You are good to go, you’ll see an output but just hit enter key to clear it.
If you want VNC to come up at start up, on your desktop go to System > Preference > Startup Applications. There put in a name for your App, the directory to the vnc.sh we just made and a comment if you want. Thats it. Not it will start up every time you reboot.