Thank you for contacting Telerik Support.
It seems that the application pool identity of the Sitefinity 3.7 site is running cannot write in the web.config folder. Check the permissions for the identity of the application pool. The identity should be able to write in the bin folder and in the site root. Then try the manual setup: Manual migration setup
Please do not hesitate to get back to me if any problems persist, I'll be glad to assist you further.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items