If it is not in the list of extensions, it is not installed.
Pressing install is supposed to show extension file at
/Users/maxi/Library/Application Support/Blender/3.6/scripts/addons/pribambase/aseprite/pribambase_aseprite.aseprite-extension
Which is installed like any other aseprite extension: by dragging into the window, or double clicking, or from preferences > extensions > install.