SQL Server 2017 installation unauthorized error
I'm using my admin account which has permissions (I’m in Administrations group ...

Let's get the obvious one out of the way ...
Did you run the installer program &quot;as Administrator&quot; ?
Just being in the &quot;Administrators&quot; Group stopped being enough to &quot;break&quot; your machine somewhere around Windows Vista!
To get into an &quot;elevated&quot; security context, wherein you can make changes to your machine, you must pass through the User Account Control (U.A.C.) &quot;Challenge&quot; by running the installer program &quot;as Administrator&quot;.