Import to XWiki from an older Confluence version: how to make it work?

Hello,

the tests I have been conducting in order to see how migration from Confluence works hit with the following issue:
each time I hit stage 5 and 6 of the migration process I hit the wall : Compute does not do anything. I only noticed now the URL to the space which was found by the Confluence migrator tool is wrong :
It shows https://confluence.example.com/spaces/IT when it should point to https://confluence.example.com/display/IT :

how can I fix it?

The context:
testing the Confluence Migrator tool in a remote Debian server test install on XWiki 14.10.11, using an export of 1 space exported from a Confluence install which is version 7.4.17.

Thanks for your kind help.