That’s how I did it (I wrote it down so in case it works I can easily transfer it to the Raspberry Pi):
Settings → System Services → JSON 3rd party addons → enter URL
URL: https://download.smarthomej.org/addons.json
Settings → Bindings → Other Add-Ons → install Smarthome/J TCP/UDP Binding
Might output No 40 be the problem?