For tourist who cannot secure accommodations, you can stay at the following places;

Meeting Room on the basemment floor, Hokkaido Government Annex Building
https://goo.gl/maps/G2HLWad9Lup

Odori Hightschool
http://www.odori-h.sapporo-c.ed.jp/products/pg101.html
https://goo.gl/maps/ooqSFZ95CdK2

Nakajima Sports Center
http://www.shsf.jp/nakajima
https://goo.gl/maps/XxrjzpEhse82

Sapporo Community Plaza
https://www.sapporo-community-plaza.jp/
https://goo.gl/maps/gkYshJX5F2n

Chi-Ka-Ho, Sapporo Ekimae-dori Underground walkway
https://www.sapporo-chikamichi.jp/news/detail.asp?id=119
http://www.sapporo.travel/find/shops/chikaho/?lang=en
https://goo.gl/maps/c6qLzorkXVB2

as of 7 Sep 2018