Is there any way to attach the Bootstrap library using this module if not using the Bootstrap-based theme?

This module assumes that you are already using a Bootstrap theme and would already have the Bootstrap library. I'm not sure why you would want to use the Bootstrap styles for a view without a Bootstrap theme.

The module will not provide a mechanism to attach the Bootstrap library files. However, if you really want to, you can copy the templates to your theme, create a Bootstrap library and attach them through the templates. These does leave the possibility that you will not get any template updates if the module is updated. And I would not recommend doing that.