Steps to reproduce the issue

create a field type gallery
create an article
add a field type gallery and choose a folder with images (e.g. banners)
save the article

Expected result

Front end displays gallery as expected

Actual result

On a windows machine (using win 10 and wampserver 64 on drive W:\wampserver64) there is an error message saying
"Warning
JFolder::create: Could not create folder.Path: W:\wamp64\www\joomla37\cache\plg_fields_gallery\gallery\4\150\W:"
Note that the drive letter of wampserver gets added to the end of the string, including the colon, which is forbidden in a path. The gallery remains empty, as there is nothing to display apart from the title (is that's enabled).

I have a second installation on a Macbook using MAMP, and there the gallery field works as expected.

System information (as much as possible)

Additional comments