I first tryed to configure the whole by reading one by one all steps to create my hotel. But ... There is a problem : when I create a room, it keeps "save" button spinning endlessly. (the same if I try to modify an existing room or copy and modify.
The same if I go to the other tabs of the configuration ...*

Where am I wrong ?

here the steps I used (if my english is not understandable upper) :
When I open "admin" backoffice pages, then creating hotel (no problem), then trying to create a room in "catalog>product" section, nor "save" and "save and stay" are aviable. It keeps spinning endlessly.
So I tryed differently. I copy the "general room" from demohotel and then when I enter in it (nameit : gr2), it has the same problem : endless spinning.

website (still in construction) : https://superdevoluy545s.go.yo.fr/HC151
install : ok. sql and server : ok.
If french speaking, it will be appreciated