Tabnine plugs into the following completion engines:
YouCompleteMe
Tabnine supports YouCompleteMe through a fork. Follow the instructions HERE
deoplete.nvim
A community plugin is available HERE
coc.nvim
A community plugin is available HERE
Not using any of the offered options?
If your completion engine is not supported - file a feature request here
If you don't use any completion engine - it's recommended that you follow the YouCompleteMe installation instructions.