why is access to users group important

I am using an account that is in the group Administrators, but also in the group Users. And I have a directory for which I removed access for the group Users.

In this directory there is an executable that when I try to run it from the explorer, gives me Windows caot access the specified device, path, or file. You may not have the appropriate permissions to access the item.

Surprisingly I get this even when I right-click the file and choose 'run as administrator'.

If I try to open it from a command prompt I get 'Access is denied.'.

Only if I try to open a command prompt with 'run as administator', and then try to run the executable it finally runs.

Can someone explain to me why this is, and what rights I can add to avoid having to start a command prompt in administrator mode to finally run this application? I would assume this all would not be necessary as I am already an administrator.