You need to locate your binary files and run the engine directly.
On Tabnine Hub, scroll down to the Engine file path, and find the Tabnine file path.
If Tabnine Hub is not opening for you, please see here how to locate your engine path.
You need to run the latest Tabnine engine you have on your computer.
The pattern should be something like: {TabNine's Folder within IDE Plugins folder}\binaries\{version}\{pc_arcitecture}\TabNine.exe
Try to run the following command from the terminal using the right path:
PATH_TO_ENGINE/TabNine --client debugging --log_to_stderr --log-level DEBUG
Then you can collect the output into a file and share it with us.
If the Tabnine engine file fails to run directly, please mention that in your support ticket.