Academic usage of this dataset is free. Research publications should mention the following remark:

“The Versailles-FP dataset is a contribution from the VESPERA research project, founded by the french Fondation des sciences du patrimoine, with the Centre de recherche du château de Versailles, the Archives nationales, the Bibliothèque nationale de France, and the ETIS research lab (UMR8051, CY Cergy Paris Université, ENSEA Cergy, CNRS).”

and cites our original paper:

Versailles-FP dataset: Wall Detection in Ancient Floor Plans,
Wassim Swaileh, Dimitrios Kotzinos, Suman Ghosh, Michel Jordan, Ngoc-Son Vu and Yaguan Qian
IDCAR 2021, Lausanne, Switzerland