So i was looking everywhere for a solution and it dawned on me what the problem was.... Swiftkit isn't updated to use the new clients so you have to go download RS legacy client.
Step one: https://www.runescap...ad/old-versions
Step two: scroll down till you see "old versions of runescape"
Step three: download your operating systems client
Step four: install it
Step five:Go into swiftkit and go to the "play RS" button and click "use RS client"
Step six: click on desired Runescape and it should load up
i noticed the last message on swiftkit was 2016 so i looked up when the nxt client came out and they came our around the same time and i noticed alot of stuff dropped java so i went and downloaded the old java one and boom its fine. i would assume that the problem we were having is the new clients arent set into swiftkits data but the legacy one is so when its launching the game its looking for the legacy client and its not there.
thank you and hope this helps. Scape on my friends!