Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Liggity's "about us" page says "We offer two different options and depending on with service you select the apps can be installed on Smart TVs, Android box, Roku, Firetv, Firestick and any android or iOS device."
So, if they don't seem to support Roku, perhaps ask them why they say they do?
Whenever I see "over 2800 channels of live TV to watch..." I'd be willing to bet they're nothing but a bunch of pirates. If so, don't expect to see a LiggityTV channel on Roku and if you do don't expect it to last long.