Transferring Itunes Library to new PC

I bought a new laptop for music and photos and wanted to transfer my itunes library to the new device. I backed up the itunes folder (including itunes media and itunes music) onto a hard drive. I then downloaded that onto the new laptop. Itunes works but my library does not show the majority of my music (I am old so most of it was downloaded from CD into itunes on PC). When I look in the itunes music folder under itunes, it does appear to all be there but for some reason the library cant see it so I cant access it. I have done it this way before several years ago when changing to the old computer. My new computer is a HP running windows 11.