Congratulations on being invited to take the Bain online test!
From what I recall when I went through the Bain recruitment process for the Associate Consultant role, the numerical and verbal reasoning tests were provided by CEB SHL:
You can sign up on their website to gain access to some practice material. If you also google CEB SHL numerical and verbal reasoning tests, you should find mock tests which are similar, from several different sources (however, be aware of the quality and difficulty of these test).
Other practice material:
Although the style of the tests varies slightly to those provided by CEB SHL, I found that https://www.assessmentday.co.uk/aptitudetests_numerical.htm was a great resource for both numerical reasoning and verbal reasoning (I would consider paying for a subscription if you're expecting lots of interviews in the near future).
For additional verbal reasoning practice, I also completed a few tests on YouTube.
Good luck with the upcoming test.