I wouldn’t say that everyone’s getting replies here except for you, sometimes things fall through the cracks but no one’s out to get you
I don’t know CauseMap, but a quick Google turned up this: https://github.com/cyrusmaher/CauseMap.jl - is this the page that you’re using? If so, it’s not surprising that it doesn’t work, as it looks unmaintained with the last commit in 2015, when Julia was (I think) at version 0.3. The current Julia version is 1.4 and many things have changed, so packages released before Julia 0.7 are unlikely to work out of the box in the latest Julia version.
This package therefore also isn’t registered in the general registry, which is what the error tells you. You can still add it from its GitHub URL to install it, but as I said it is highly unlikely that a package written for Julia 0.3 will work in 1.4. If you absolutely do need this package, you are of course free to install an old Julia copy and run the package from that!