Get the file "mathematica.sh" after download?

Hi guys, I am having troubles with the installation of Mathematica on my new desktop.
I had it previously installed on my laptop, now I have a new one, and I have eliminated Mathematica on my previous computer.
The problem now is that when I try to install the “file.sh”, needed for the installation, it results at the end “missing or moved”.
I don’t understand the reason for this, but for sure it is a problem since without that file I can’t download Mathematica.
Any suggestions about a possible solution or reason for this problem?
Thanks in advance for your time

i had a similar issue: the installer installed Mathematica, i then attempted directly after to install wolframscript but it said i couldn’t install wolframscript as it wasn’t downloaded

however install instructions for macOS Sierra said “sign in / register” THEN install wolframscript

after that: it worked for me