A "Unable to Mount Location . Failed to Mount Windows Share" is usually a permissions problem on the server. Not a Samba permissions error - a Linux permissions error.
If you can access the share without presenting credentials then you are accessing it as a guest ( the user "nobody" ). So the question is does "nobody" have access along the entire path to the shared folder on the server?
I know nothing about Raspberry Pi but is there some way you can get from it the output of the following commands:
Then we will all know how things are set up and what's being shared.
net usershare info --long