From this link you can download/clone the dutch language pack (version 1.0.3 ) https://github.com/Adwise/magento2-nl_NL-language

You can also download version 1.0.3 from this link

Then run the following


Copy all files to the directory app/i18n/adwise/nl_nl/ and then execute the CLI commands:
 php bin/magento setup:static-content:deploy
 php bin/magento setup:static-content:deploy nl_NL   ( change to your own locale )
 php bin/magento indexer:reindex
 php bin/magento cache:clean
 php bin/magento cache:flush