It is not possible to tabulate within a table of In 2020. When you perform Control + Tab, you jump and open another document in the background. Tabs can only be entered manually via the Type - insert spicial charecter - tab .
In the previous version 2019 when I used shortcut of ctrl+tab the tab was adgusted and the defenition was kept and I was able to place text the way I wanted, now when I press ctrl+tab as I mentioned it throws out to other doc