Vector brushes not visible

I agree with Michael, a screenshot of what you're seeing would be helpful here.

It may take two taps to show the brush choices. First tap selects the brush type, second tap opens the panel to choose alternative brushes.

If you don't see the three brush types on the left as per this image

then we have a different issue to try to solve.

In addition to that, you can only add brushes to the pixel brush area at this stage.

Can you show us a screen shot of your interface, with the vector brush tool active and the brush panel showing? This may help us see the issue.