You can use a chevron
<< to the left of the folder navigation breadcrumb in case there is no room for all of the folder names. Push the parent folder names to the left giving priority to the child on the far right.
However for very long names, you can set a standard maximum length for the characters that should be displayed for each folder name(giving priority to the child too) when there is no room between the breadcrumb and actions/controls to the right, use an Ellipsis
... to signify the adjustment.
You can also chop off some characters on the child incase it is very long or you want to leave enough space between the breadcrumb and the actions.
In case the user wants to navigate back uptop, they can click on the chevron to reveal the parent names. It can be a dropdown or horizontal scroll for the folder names.