re: the dialogue: You do not have enough access privileges for this operation Error code -45054
A fellow musican I know had an identical issue with this and asked me to check it out. I fixed it and wrote a long set of instructions on my blog. His problem was with 10.6 but it was an update he did preparing to move to Mavericks.
I was able to reproduce the error by just removing the /Shared folder from /Users
Here is the link to the problem and the instructions on how I fixed1t
In order to comply with this form, I must point out that the fixed1t blog site does sell cheap Garageband and sampler support software and that I will benefit if you buy it. The reality is, nobody buys these days LOL ;-)
If the folder already exists then ignore the mkdir command and skip to chmod
Open the terminal and go straight for the:
To make the folder fully accessible your use the Unix Command chmod to and set it to the folders permissions and privileges to 1777 (if your running Mac OS 10.6 as I am here). If your running Mac OS 10.5 use the code 777) These codes give the shared folder a kind of 'Universal Donor' status so it can be used by other programs and processes, sort of permissions to all.
So at the Terminal Prompt now type:
sudo chmod 1777 /Users/Shared
Follow this by Return, then quit the Terminal.
Try iTunes again. If it still fails open the disk utitlies and repair the priveleges then restart and try again.
I hope this helps.