Thanks for letting me know you're using a Chromebook. I have some more resources for you.
It's true that the article I sent you before didn't have explicit keyboard instructions. I wanted to give you a general reference until I learned more about your specific setup. I hope to resolve any confusion that may have caused.
# Open the bookmark manager using ctrl + shift + o. This opens the bookmarks manager in a new tab and puts the focus in the "Search bookmarks" box in the bookmarks manager.
# Use tab + enter + esc keys to move around the bookmarks manager.
# Close the bookmark manager by using the keyboard shortcut to close tabs, ctrl + w or to close the whole window using ctrl + shift + w.
You can also use tab to move forward and shift + tab to move backwards on the page. You can use the space bar or the enter key to expand menus.
I hope that helps. Please let me know if you have any more questions.
Thanks,
Laura