The single bay/single drive My Cloud units are very limited in what they can do. They do not officially support downloading/uploading to cloud (online) based services. It’s possible the multi bay My Cloud units may have some capability to do so .
Unofficially Goodsync is the way to go. But as you found out you have to hack the firmware to install the Goodsync package. You may not like that workaround but it is one method to possibly achieve what you desire/seek.
Or one could setup the cloud based app on a computer and with the use of WD Sync or similar sync program (like Free File Sync) setup a system to download/upload to the cloud from the computer and have the computer sync its data to the My Cloud.
Since this is mostly a user to user support forum you may want to place your complaint/request in the Cloud Ideas subforum or the Software and Apps Ideas subforum.