Same way you installed Kodi. Use the Downloader app to install the APK for Titanium TV
Could be a number of things
Your ISP is unlikely to block you specifically from using it. They may however be blocking some of the content providers, especially any outside the US
Most likely your add-ons are out of date. Your repositories are probably out of date as well.
The version of Kodi that you are running probably won't affect playback, but will definitely affect scripting. The scripting is what the add-ons use to find streams. So while you don't necessarily have to update Kodi to Krypton to play the video back, you probably should update it to keep your add-ons up to date.
Oh, and there was a massive security bug a year or so ago. So it might be time to update