step1:Upload files that contain [#] in the file name from Dynamics 365.
result:Upload Complete.

step2:Download files that contain [#] in the file name from Dynamics 365.
result:404 Not Found is displayed and cannot be downloaded.

step3:If we use share Point, we can also download a file that contains [#] in the file name.

note:
We have checked from past documents that [#] is a forbidden character for the file name.
Some customers use the # sign. I would like to be able to use the # symbol in general for Microsoft products, not just in Dynamics 365.