Just to clarify: Line Up mode doesn't use a keyboard — you tap the buttons to reveal words/lines.
If you're using Typing mode (where you type out the verse), you need to tap the colored box in the center of the bottom toolbar to bring up your keyboard. This box displays the letters you're typing and is located between the hint button (left) and the back button (right).
The box will pulse subtly when it's not focused, which is your visual cue to tap it.
Once you tap it, your Gboard keyboard should appear and you can start typing.