How to sync music to new ipod classic 6th gen

I have just bought an ipod classic 6th generation but am having trouble adding music to it. I contacted Apple Support who just pasted what to do and did what was recommended but it's still not syncing. Yesterday, when I initially downloaded itunes onto my new Windows PC it showed music that I'd purchased. Later on itunes said music can only be obtained via Apple Music and no music was showing on itunes. I've downloaded Apple Music and Apple Devices and selected to automatically sync music but it's not doing anything. Note that I don't have an Apple Music subscription. It's also worth saying that a few years ago all of the CDs I had put onto my old computer stopped showing on itunes too, so I think I may have lost a whole lot of music. I did copy the library onto two external hard drives but when I tried to put the music onto my ipod it didn't work. When I go on Apple Devices my ipod shows but when I click Music it just shows the turning "thinking" wheel and nothing else. I don't want to buy music when I've already bought it years ago. My questions are:-

1. Do I have to have an active Apple Music subscription to put my library onto my ipod?
2. Can I put my music that's currently showing on Apple Music onto my ipod 6th classic 6th Generation and if so how?
3. Is it possible to locate all the music I uploaded to my old laptop and put it on my ipod?
4. Can I put the music that's on my external hard drive onto my ipod?
5. Am I wasting my time and really I should return my ipod for a refund?

Thank you!