You should make sure that you copy the files from your deployment folder to your new project. So you should copy the deployment/data folder from your previous application folder to this location:
C:\Users\jb\Mendix Documents\BM Projects\TeleMendix-main\deployment\data\
The -main part tells me this is a new folder of a 3.0 project and that this project is under version control, so I'm not entirely sure how it was merged from 2.5.6, maybe something isn't done correctly when migrating and putting something under version control like this.