I am now trying to download the official version of Mojave from the Google Drive. It's a zip file. I have downloaded a bz2 file trough torrent that was corrupted, then I download another bz2 directly from media fire, but this one has be unpacked to a raw file that I can't open either. I tried to cover with VBoxManager but it can't recognize the internal format... I'm out of ideas, hope the zip file will have some ISO, DMG or IMG file...
I needed to downgrade my Catalina to Mojave. Catalina is a bad OS, without bothering you with details, and my Macbook can't upgrade to Big Sur, so there is no point I keep with Catalina that won't run 32 bit apps! But Apple does not allow this anymore, me and a group have researched for an official source of the installation volume but it's not available anywhere at Apple anymore (a long thread about it in Apple's support forum). I also have a bad feeling about Apple's intentions, but won't bother you with this either, just need a Mojave to flash my USB stick and go on.
Thanks!