Love that there's a temporary implementation of Jagex accounts. It's still buggy. It after opening 2 or 3 times, the Jagex launcher quit working completely, had to uninstall it and reinstall. I chose the repair Jagex Launcher option first, with no success. So I just reinstalled. Running on Windows 10.
(Edit)
I realized I was doing it wrong. I found out you don't have to click the "Launch stealth with Jagex Account" check box every time. Doing this made me sign into the launcher on every launch, which was super annoying. Then finally I used the Jagex Launcher to launch my accounts after I patched the client. This opens the OSbot boot then all you have to do is click Stealth, and it will load with no problem. Hope this helps anyone else who had a hard time at first.