Re beta, sorry, misread the OS version. :-/
Not sure what you mean by the container. You can either run it while booted to the same hard drive you are analyzing (which can be problematic at times), or you can run it while booted to the Mac Recovery partition.
About macOS Recovery - hhttps://support.apple.com/HT201314
Disk Utility can only repair so much. If it can't handle this then your alternatives are to restore from a known good backup, or try a tool such as Diskwarrior which is costly. It is pretty good but it's a gamble since the last tiem I checked there was no trial version.