My cloud completely locked up my Mac so had to disconnect and uninstall

On my mac I have a Seagate 2Gb external hard drive. I also have a Dropbox account which I used for many years. My plan was to replace Dropbox with the WD My Cloud.
My first issue I discovered by close examination of the documentation is MyCloud does not sync. It is a backup which you are supposed to be able to access remotely.
Then the big problem arrived. My computer started going slower and slower until it became unusable. The rotating disk symbol was displayed permanently and I could hear the hard drives working all the time.
The fault seemed to start when I went on line. So I deleted and re-installed Chrome. On startup the fault did not appear but did so after a couple of minutes.
I thought it was a virus but my local PC repair shop assured me the symptoms were hardware not software. Probably loss of memory or memory full. The advice was to remove the external hard drives one at a time to see if the fault disappeared.
First I removed the Seagate. No change.
Then I disconnected the WD and then realised that did not turn off the wifi. So I disconnected the power.
Problem solved.
Since then I have uninstalled all the WD software.
My Mac is now fully functional with no speed issues.
I am not a computer software expert by any means but job for years has involved installing solving customer problems with my product’s hardware and software.
Installation of WD software although not particularly elegant or intuitive is not overly complex so I confident the procedure was followed correctly.
To put it mildly, I am not happy with WD. Their description of the My Cloud is not clear and dubious. It certainly cannot replace Dropbox.
Any comments on what I may have done wrong would be welcome.

WD My Cloud has been reported several times for problems. Stick with dropbox.