Did you have a standard iTunes installation on your PC, or had you customized, which means some of your iTunes installation was somewhere else on your PC's hard drive and so did not get transferred over? I had that situation and had to be very careful. I first looked at the iTunes file structure on my new iMac immediately after installing iTunes and before copying any files from my PC. Then I carefully built a duplicate file folder structure on an external hard drive and went through my PC's hard drive to find and copy all the necessary files to the external hard drive. Then I copied those files to my iMac. I had to start over a couple of times until I got it right. These links helped:
iTunes: Back up your iTunes library by copying to an external hard drive
iTunes: How to re-create your iTunes library and playlists
iTunes: What are the iTunes library files?
Move an iTunes library from a Windows PC to a Mac | Macworld
For what it's worth (your situation could be different), here are the notes I made to prepare for my successful iTunes migration:
Check that you have the same version of iTunes on both the PC and Mac.
On PC:
Check contents of C: > Users > You > Music using Windows Explorer:
iTunes
Album Artwork
Cache
Download
iTunes Music
Previous iTunes libraries
Playlists
Check location of iTunes Media folder:
Open iTunes
Edit > Preferences > Advanced: D
iTunes (Should be called “iTunes Media”)
Quit iTunes
[Optional note from a non-Apple website: if your music isn’t stored in the default location on windows you’ll have a database and library files in the iTunes folder in the regular location, and an iTunes Media folder elsewhere. After copying the C:iTunes folder to an external hard drive, copy your D: iTunes Media folder into that the iTunes folder. Copy all of that to your Mac, and launch iTunes. As before, it should work fine.]
Check D
iTunes folder contents using Windows Explorer:
Automatically Add to iTunes
Books
Downloads
Mobile Applications
Movies
Music (all my music)
Podcasts
On Mac:
Check contents of Music folder (all empty because it was a new iMac):
Album Artwork
Cache
Download
iTunes Library
iTunes Library extras.itdb
iTunes Library genius.itdb
iTunes Media
Automatically Add to iTunes
iTunes Music Library.xml
Open iTunes on PC.
Edit > Preferences > Advanced.
Select Keep iTunes Media folder organized.
Select Copy files to iTunes Media folder when adding to library.
(After you click OK, iTunes copies any files that are added that weren't already in the iTunes Media folder and places the copies in the folder. The original files are left in their original locations. To save space on your hard disk, you might want to delete the original files after confirming import.)
File > Library > Organize Library.
Select Consolidate files.
Quit iTunes.
Open windows Explorer - three instances.
. Locate iTunes folder in C: > Users > You > Music
. Locate iTunes Media folder [on my D: drive, called iTunes but should be called iTunes Media].
. Locate destination external hard drive.
Drag the C: > windows > Users > You > Music > iTunes folder to external hard drive.
Drag the D:iTunes folder into the iTunes folder on the external hard drive and rename it to iTunes Media.
Quit iTunes on the Mac: iTunes > Quit.
Open a Finder instance for the iTunes folder on the Time Capsule.
Open a Finder instance for the Music folder in Users > Your user folder.
Drag the iTunes folder from external hard drive to Music folder.
Open iTunes while holding down the Option key.
Select Choose Library.
Select the new iTunes folder.
Click Choose.
iTunes should be restored.
[Optional note from a non-Apple website:
Launch iTunes on Mac.
Edit > Preferences > Advanced.
Click Change button next to iTunes Media Folder Location.
Navigate to the iTunes Media folder and click OK.
iTunes will now look to that drive for your content, and everything should be working correctly. If not, choose File -> Library -> Organize Library, and consolidate the library as above to fix any problems.]
When you close down your PC for the last time, head back into iTunes and de-authorize that machine. iTunes library can be on up to 5 computers. If copied the iTunes library to the Mac, then the original remains on the PC as a backup frozen in time.