PhotoCopy will work with free Flickr accounts. Some of the limitations of free Flickr accounts affect PhotoCopy as listed below:

Photostream views limited to the 200 most recent images

This limitation effectively means that PhotoCopy can only handle up to 200 images.

When you select 'All photos', PhotoCopy tries to copy all photos in you iPhoto library to Flickr. Do not select 'All photos' if you have more that 200 images in your iPhoto library

Only select albums to copy where the total number of photos in all the albums is 200 or less.

100 MB monthly upload limit (10MB per photo)

PhotoCopy will not be able to upload items past the 100 MB monthly limit. Nor will it be able to upload single photos greater than 10 MB in size.

3 set limit

Since a free account only allows 3 sets, PhotoCopy will not be able to create sets in excess of 3. You should only check up to 3 albums in the album list for PhotoCopy to copy. Also, if you have created any sets in your free Flickr account, those will affect how many sets PhotoCopy can create. For example, if you have 1 set in your free Flickr account, PhotoCopy can only create 2 additional sets.