User quota problem with shared folder


I have created an user with only 1MO of space (with user quota), but I want to allow him to write into shared folder. When copying a file larger than its quota on the seadrive, It has the following windows error

There is not enough memory to complete this operation.
Size free : 1024ko
Total size : 1024ko

Note that in windows, the disk appears with a size of 1mo.

With the web interface, I can upload files of more than 1mo into shared folders but not with the drive.

Is this normal?
Is there a solution?