Only access to one shared folder?

I would like to have folders with different access. So there is a folder for the normal projects where most of the people of the company have access to and there is a folder for the administration, where only a certain amount of people have access to.

So I have those two shared folders:
company_projects
company_admin

And I have two users groups:
company-management (can access both folders)
company-general (can access the projects folder).

However, I am currently testing and only I have access to the server at the moment. I was able to access the folder company_projects without any problems and I have already transfered a few GB to this folder. Now when I try to open the newly created shared folder "company_admin" I am asked to provide my credentials and when I do it, it says that access is denied. I still can access the company_projects folder though.

I think the permissions are set correctly.

Seems like I found the problem.

I had added myself to all groups created, as I felt that I must be able "to see everything". But of course, if I exclude one of the groups I am in, the server has a conflict and probably it is solved by just not letting me in.

Is this assumption correct?

So basically I should add my user mainly to one group, correct?