You may want to post in the dedicated EX Series subforum where there may be people more knowledgable about the EX4100. This subforum (My Cloud) primarily is for the single bay My Cloud devices.
https://community.wd.com/c/network-attached-storage/my-cloud-expert-series
Also you may want to visit the recent Goodsync thread posted below in the My Cloud subforum which may contain other install information. Note that certain single bay My Cloud units have a different firmware than those used on other WD devices as such teh commands to install the app to a single bay My Cloud may not be the same as the multi bay My Cloud units.
https://community.wd.com/t/app-goodsync-for-wd-my-cloud-backup-and-file-synchronization/173984
