Folders aren't sortting

Hello,

I am not sure if this is a “feature” of the free version but the sorting by name is way off. Instead of going 1-13 it goes 1, 10,11,12,13,2,3,4,5,6,7,8,9
When you hit Name on the top to sort, nothing happens.

https://ww.wp.xz.cn/plugins/sp-client-document-manager/