You need to create a snippet that retrieves the logged in user name and puts it to a hidden field in "doc manager" (what is that snippet btw?).
E.g the snippet would be getWebUsername: <?php return $_SESSION[’webShortname’]; ?>
And in your doc manager form template you would have a hidden field (some of the existing fields if they are unused, like summary field or a TV):
<input type="hidden" name="summary" value="[!getWebUsername!]">
Then use a MaxiGallery call like this in the gallery documents what get’s the user name via
getField snippet:
[!MaxiGallery? &display=`embedded` &admin_webusers=`[[getField? &field=`summary`]]` &embedtype=`slimbox` &pics_per_row=`3` &thumb_use_dropshadow=`1`!]
If the doc manager snippet puts the webuser as the author of the document, you don’t need to do the getWebUsername at all, just retrieve the document author with getField to maxigallery.