The Border Buddy can be found in a panel in the output properties. Make a snapshot of the current render border in camera view by pressing '+', give it a name and retrieve it again by selecting it from the list.
This extension does not require special permissions.
Sure, here is the translation:
"I sincerely say that using the basic tool is quite difficult because the content of the instructions is still vague. You should have said: 'Select the object that needs a border -> click + in the "Border Buddy" section -> click "Store Border" at the bottom of the "Border Buddy" section...'"