How to get rid of the ERR_TOO_MANY_REDIRECTS problem with a new domain registered at Cloudflare but hosted in Siteground

Go to Cloudflare SSL/TLS for the relevant domain
Change to FULL ENCRYPTION MODE

Also use these plugins (once you can see wordpress): https://developers.cloudflare.com/ssl/troubleshooting/too-many-redirects/#edge-certificate-settings

The ERR msg was solved but it turns out that the A record of Siteground that I had copied (from somewhere on the internet) was wrong. It had to be changed – which finally made the site online.