Error I can't run this script (Vivaldi - HTML5 Proprietary Media)

Getting to the point, I like a browser (vivaldi) except it’s not available on flatpak, so I downloaded the RPM package from their website and installed it via rpm-ostree. But I need to add proprietary media for everyday use, I need to run a script but this is not possible in Silverblue.
For this it is necessary to enter this page and follow its steps (, but when executing the command in the terminal returns me this:

Can anyone help me so that I can run this script and install the proprietary media?

The solution is at this link: