Hi create_share,
to resolve this error, you will need another folder from another server that has windows-server-backup feature working.
So, you will need just copy the folder WinSxS from C:\Windows\WinSxS and paste it to the server that is getting this issue with windows-server-backup feature. Then you open CMD and run this command:
Dism /Online /Enable-Feature /FeatureName:WindowsServerBackup /Source:C:\WinSxS /LimitAccess
Hope it helps.
Regards, Lei