Sure, i have already put the files in there with root access
Ahh, ok, so that the problem. FTP users can not upload or change files when you uploaded them as root user. The root user is the administrative user of a Linux server, files that are uploaded by him vcan not be changed by normal users. To fix this, you have to chown all files and folders recursively to the web user and client group of this website.
chown -R web1:client1 /var/www/www.domain.tld/web/*
replace web1 with the web user that owns the website and client1 with the group that owns the website. You can find client and group on the options tab of the website settings.