In case anybody needs them, these are the exact file sizes and checksums, and links to the download pages:
Windows (full installer):
https://www.hauptwerk.com/win/
MD5 checksum: f5c1ad57e068fcf6382bef510804b083
2.99 GB (3,214,412,632 bytes)
macOS (full installer):
https://www.hauptwerk.com/osx/
MD5 checksum: b52d0c82f533728e6402d45a4c972668
3.14 GB (3,377,089,757 bytes)
(If you have any problems installing, please first verify that file size and MD5 checksum of the downloaded file are correct. If not the file didn't download properly -- please try downloading it again. Thanks.)