Not sure whether this was the original issue, but the infrastructure hosting SnpEff and its databases seems to have issues since at least 12 July.
The author of SnpEff is aware of the issue, which seems to persist since the beginning of the week and seems to be seeking help from Microsoft, who are hosting the data.
see Databases not available? July 12, 2025? · Issue #596 · pcingola/SnpEff · GitHub
Until this is resolved there is just no way to download SnpEff databases whether through Galaxy or the command line.