Network password to access folders?

Hi, very new to all this, have it working and used Acronis to back up to the time machine folder.
I can access on my network the public folders.
When I try to access for example WDsync a box pops up asking for Network password, user name and password.
I have tried the one I made for MyCloudEX2 i.e admin and then the password but this fails.
The manual says to enter your router credentials, this fails, I have tried my windows log on details and yes that fails as well.
Please can someone help me with this, what is it after?

You can access content thru the WD sync software. Here is a KB article explaining it - https://support-en.wd.com/app/answers/detail/a_id/19658