I use Acrobat Reader and an application called "Box for EMM" on my iPad.

(1) From the top screen of Acrobat Reader, tap "Browse for other files"
(2) Tap "Box for EMM" from "Location" on the displayed screen
(3) Since the file list on Box is displayed, tap the PDF you want to refer to
(4) PDF is displayed
(5) Tap the "<" mark on the upper left of the screen to close the PDF and return to the top screen of Acrobat Reader.
(6) If you tap "Browse for more files" again, you need to select "Box for EMM" from "Location" again

In previous versions of Acrobat Reader, after closing the PDF, tapping "Browse for more files" in (6) allowed you to return to the Box folder that was displayed earlier.
However, in the current version, starting from selecting "Box for EMM", the deeper the folder hierarchy of Box, the more inconvenient it is to go through it one by one.
Therefore, in (6), even after closing the PDF, we request that you improve the interface so that you can return directly to the originally opened folder.

By the way, the version of Acrobat Reader I am currently using is as follows.

Acrobat Reader: 23.03.01
Box for EMMs: 5.9.0
iPadOS: 16.4

Thank you.