These are the data loading instructions: https://wiki.galaxyproject.org/Support#Loading_data
If the data is over 2 GB in size, you just use the URL or FTP loading method.
If the data is over 50 GB in size (uncompressed), then it exceeds the dataset size quota for upload. Local or cloud Galaxy use is recommended.
If the data is compressed (gz), consider trying to load these uncompressed since it can sometimes resolve the problems.
If the data is a compressed archive (tar.gz), then this will either fail or just the first file out of the archive will load. Instead, unpack it locally and load the files individually. This is very easy to do with FTP and a client like Filezilla.
Hopefully one of these helps to resolve the problem! Jen, Galaxy team