2021/05/17 15:01:36 DEBUG : PROPFIND /test HTTP/1.1
response
2021/05/17 15:01:36 DEBUG : HTTP/1.1 404 Not Found
so rclone tries again with a / on the end
2021/05/17 15:01:36 DEBUG : PROPFIND /test/ HTTP/1.1
response
2021/05/17 15:01:36 DEBUG : HTTP/1.1 404 Not Found
So then rclone tries to create the directory
2021/05/17 15:01:36 DEBUG : MKCOL /test/ HTTP/1.1
and we get
2021/05/17 15:01:36 DEBUG : HTTP/1.1 403 Forbidden
<h3>You do not have permission to view this directory or page using the credentials that you supplied.</h3>
So it really looks like that user doesn't have permission to make directories on the server.
The difference with the mount trace is this
2021/05/17 15:06:41 DEBUG : PROPFIND /dompie/testdir/ HTTP/1.1
response
2021/05/17 15:06:41 DEBUG : HTTP/1.1 207 Multi Status
(data)
Can you look in the IIS logs to see what caused the 403 error when you tried it with rclone copy?
Probably the thing to do next would be to the same operations with mount and with copy with -vv --dump bodies and try to compare the HTTP transactions to see what the difference is.