Just to improve on the above suggestion a little bit, you don’t need to manually cat or edit any connman files - in fact you should not edit connman files directly. Instead to check if wifi is enabled:
connmanctl
then
technologies
If wifi is off use:
enable wifi
then
scan wifi
then
agent on
then
services
This will list found networks, then use connect with the long string to the right of the network you’re trying to connect to - for example
connect wifi_c83a35ca4314_535454657374_managed_psk
Tip: you can use tab completion so you don’t have to type every character.
Once connected the connection will be remembered and automatically used in the future.
Network settings will soon be added in the OSMC settings addon so this manual method (or entering the details during install) won’t be needed for the final version of OSMC.