Giving it the .app should work, what's happening instead in your case?
I had an error message: "Unable to create the installation medium"
To fix, I regenerated the media to a USB key with the proper commande and this time it worked...
Me as well, cannot install the latest Catalina beta.
Getting the following error "Unable to create the installation medium"
2 people found this helpful
Create your own install media:
hdiutil create 1015.dmg -size 8g -layout SPUD -fs HFS+J
hdiutil attach 1015.dmg -noverify -nobrowse -mountpoint /Volumes/InstallCatalina
sudo /Applications/Install\ macOS\ Catalina\ Beta.app/Contents/Resources/createinstallmedia --volume /Volumes/InstallCatalina
hdiutil detach /Volumes/Install\ macOS\ Catalina\ Beta
hdiutil resize -sectors min 1015.dmg
Use the 1015.dmg in Fusion.
This worked perfectly. Thank you!
You should accept the answer using hdiutil as that resolves your issue.