For Thunkable log in options, please contact Thunkable ( https://community.thunkable.com/
This is the App Inventor 2 Forum. Thunkable is a third party clone of App Inventor and is a commercial endeavor. They can best answer your questions about Thunkable login.
Mixing App Inventor and Thunkable aia files and code can result in unintended consequences. The problems include file corruption, inability to load a Thunkable developed aia successfully on the App Inventor 2 server, and app instability depending on the components used with each compiler that may not exist on the other., We strongly recommend that if users develop on one platform or another to STAY on that platform for any one Project, especially if developing in a teaching environment. Mixing compilers does have unintended consequences.