Hey! Quick headsup.
I ran into a bizarre problem on a fresh new macos install: I constantly was getting IS-0007 problem, unable to download anything, and getting insta-broken installation no matter the engine version.
No amount of reinstalling and cache clearing solved it, and yes - i did have full disk access enabled for launcher.
All is not lost however, the problem got solved with a rather simple cave-age technology: i went out and manually created the folder the bug was referring to [in my case, it missed Manifests > Pending folders] and voila.
Have a nice day, and hope this helps.