Press R for Retry
As it seems the Devil was in the Machine indeed:
somehow I managed to upload the Beta#4 archive renamed to Beta#5 for the AmigaOS4 package.
The file is corrected on SourceForge, please download it again from the Beta#5 folder:
The other packages were fine, it was a problem only with the AmigaOS4 archive.
Apologies for wasting your precious data...
Thanks to Chris Handley and Karsten Larsen for bringing it to my attention.