Depending on which path you have taken for backend installation before with the current server you can update your backend to the latest version from the same path as guided below.
To update the backend you would have to first remove the volume created for CMS assets (translation, logo, etc.) so the new assets would replace the old ones. Keep a backup of volume contents if you need to.
docker volume rm root_taxiassets -f
Running the above command would remove the volume. Now using the below command backend & CMS would be updated to the latest version.
wget -qO- https://uploads.ridy.io/docker-compose-flutter.yaml > docker-compose.yaml && docker-compose pull && docker-compose up -d
Then login into the dashboard in some cases if required to configure you will be redirected to the configuration page.
With each new version, client codes are usually subject to updates so it would be better if you had your Version Control system in place with one branch being the files downloaded from Codecanyon and the other one your customizations. This way you could release with each new release that comes and resolve conflicts easier.