Help with permission and accessing files on Windows (SMB)

Hi All,
I have been reading through all the documentation on SMB shares and I have run into a problem and I don’t know how to fix it.
I have two Datasets one is HaztisNas and one is Plex. The original HaztisNas works fine and I have full access and control. I know when I setup the SMB share I had to create a username and password but for the life of me i can remember how to it again for the Plex dataset so I can have full control and add and remove files within windows as I need to.
Can anyone help please.
This is the message I get when I try to add file to any folder within plex.

I can see all the folders in the Plex folder in windows as I just can’t access or added to them.

Thank you.

You should stick to your original thread since this is related and you have screenshots, etc. there.

Thanks Smallbarky.
No one has responded since my last comment so I thought I would start a new topic for a hopefully faster response.