For web accessibility, I want to activate it when accessing the menu with a tab.

Hello,

Thanks for your Patience!

While this is not included with Canvas at the moment, this needs to be activated and coded manually. You can simply add the tabindex Attribute with sequential ordering to the .menu-link Element. Example:
[ch_pre]

• Home

• Features

• Services

• Contact[/ch_pre]

Since, currently Customization related Support is not included with the License according to the Item Support Policy: https://themeforest.net/page/item_support_policy . You will need to manually code this or Hire Us to help you out with Customizations.

Hope this Helps!

Let us know if we can help you with anything else or if you find any further issues.