Hi Gilles and welcome to our community! 
Sorry you had to spend a few weeks struggling to install Discourse. Did you follow the official install instructions? If not and you are not already familiar with the technology stack we use, then you can expect to have a long journey getting acquainted with it.
So I guess now you are a Discourse expert! 
I see scaleway.com is not on the recommended list. @merefield can you add a reply there to suggest it, if you recommend it?