Why can't I copy and paste files from Mac Studio internal drive to an external HDD with read-only staff permissions?

Hello,

Why can't I copy and paste files from my Mac Studio internal drive to an external HDD why do I have to drag and drop? Why can't I just copy and paste? I hate to drag and drop!!!

Both drives are APFS. 

I copy and paste all the time from my Mac Studio 512GB internal to another 2TB external APFS HDD drive all the time with no problems.

The permissions settings on this 2TB external APFS HDD drive is read and write for administrator (aka my name) and read and write for staff and  read only for everyone.

The permissions settings on the 18TB external APFS HDD drive that I can NOT copy and paste to are read and write for administrator (a.k.a. my name) and read only for staff and read only for everyone.

I couldn’t find a paste option anywhere, including by trying a Command-V action.

And when I try to change the staff permissions to read and write like the permission settings are set on the 2TB HDD on this 18 TB drive it tells me I don’t have permission… I’ve tried everything.

I also tried booting to this 18 TB external drive, but it only shows permissions for administrator and wheel and everyone there is no staff permission to change to read and write like on the 2 TB drive settings.

I even tried logging into my other two users on this 18 TB drive and it’s the same as I just mentioned in the previous paragraph.

In users and groups on my Mac, there is one user that is administrator which is my name would adding another user to this help me to do what I’m trying to do?

I’ve spent many days and so much work on this hopefully somebody out there can help me out because I really need it!!! 

I hate dragging and dropping!!!

Thank You!!!

[Re-Titled by Moderator]