Have same problem.
I purchased plugin in September.
On product page no any description about compatibility with jdownloads.

Hi!
I just purhased Jdownloads extension for ArtioSef.

Problem №1.

It creates links with duplicate category:

For category "Security"
site.com/security/security

For category "Security - Antivirus"
site.com/antivirus/security/antivirus

For file "Sandboxie" in category "Security - Antivirus"
site.com/antivirus/security/antivirus/sandboxie

Problem №2.
When I opens sitemap using xmap a couple urls have additional prefix "sitemap" instead duplicate category:
site.com/sitemap/security/antivirus/sandboxie

After that this prefix displays on site too (not only sitemap page)
site.com/sitemap/graphics/converters/fre...e-convert-and-resize
site.com/sitemap/graphics/converters/foto2avi

When I opens sitemap using Jsitemap Pro some urls have additional prefix "all-categories" instead duplicate category
site.com/all-categories/system/hard-disk...-wizard-home-edition
but some urls displays with duplicate category
bestwinsoft.com/cad-drawing/graphics/cad...angular-door/summary

It seems, that urls that are not present in sitemap have double categories in urls.
Here example:
I purged all urls.
Then I opened sitemap.
Most urls looks fine - like
site.com/all-categories/system/hard-disk...-wizard-home-edition

Then I created new item in jdownloads component and opened category with this item.
Url looks like
site.com/image-viewers/graphics/image-viewers/xnview