Well @tcecyk pointed to the post leading to a solution in that case Post #28… but I felt you needed to follow the background Edit @jan545651 of getting started with adb.
That may not be the “only way” … I think it will be trial and error where you can get a mount point.
My experience with Samsung and TWRP goes back to Oreo where encryption seemed not an issue … encryption became a bigger issue at Android 10 (Q).
Samsung is specifically mentioned in this post Why doesn't TWRP support encryption on my device? from the TWRP FAQ on the subject of encryption.