Please add a colour-bucket tool or inform me on how to use it

I just started learning how to make logos with custom grids on Vectornator (like in Illustrator). I made a grid like in Will Paterson’s video as an example.

In a grid like this, the designer fills out the spaces in it to create whatever logo they’re willing on forming.

I went to try it out, but then I couldn’t colour-bucket tool for this to work… Is there actually no filler tool in Vectornator or is it just me who couldn’t find it?

*Conclusion: If there’s a bucket tool in the app, please tell me how to find & use it. If there isn’t, adding this feature would be extremely vital for better designing experience.