The only thing I can think of then is that you have the wrong version of Confluence for your version of Kodi. If you can't get it to update or even download, you might want to try
xonfluence
I see you also asked in the Kodi forum. If you get an answer there, please post it here for other members who may have the same issue.
PS. If they ask for your log, be sure you don't have any infringing addons on your device or they will not provide any help.
PPS. Here is a tutorial on how to install Confluence on Krypton. Note that you have to use the Confluence skin by Jezz_X