When I try to open gmail from my browser using Oracle VM VirtualBox, I can't log in and it crashes.

First of all, please try to use "Private Browse" mode or another web browser.

If the issue solve in this way, please clear caches in your browser to avoid crash.

If the issue does not solve, we recommend to ask for the teacher of the class.
(We may not be able to answer questions about usage of each software.)