Zerotier on Pop os

hello saw tom’s new video and want to test zerotier but get problems but the institution on Pop os

*** Package installation failed! Unfortunately there may not be a package

Have you added their repository ( to your /etc/apt/sources.list?

They also provide an installer script that does this for you, see their download page.

Yes I have done all this and I have it in my list

but I still get the error message