Looks like the session token of your active mediafire.com account has expired but for some reason JD did not recognize this.
Refresh your mediafire.com account or deactivate/delete it from JD then you should be able to add that mediafire.com folder.
If it still doesn't work:
I've found another bug in the mediafire.com folder-crawler which will be fixed via the next CORE-update.
In the meanwhile you can collect all single-file URLs manually and add those manually to JD.
Bitte auf das nächste
CORE-Update warten!
Please wait for the next
CORE-Update!
Wartest du auf einen angekündigten Bugfix oder ein neues Feature?
Updates werden nicht immer sofort bereitgestellt!
Bitte lies unser Update FAQ! | Please read our Update FAQ!
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Are you waiting for recently announced changes to get released?
Updates to not necessarily get released immediately!
Bitte lies unser Update FAQ! | Please read our Update FAQ!
-psp-