It sounds like you have some other options available. Have you seen the spindle working under power before you bought it? I just didn't want to hear that you had gone out and spent a ton of cash only to discover that the spindle was in fact, in need of repair.
I don't know why I said I might be interested in the VFD. I forgot that I have a 4 pole motor.
I think I found an add for your VFD
https://www.aliexpress.com/item/7-5K...900234584.html
They don't give a number for maximum output amps, and say that it's only suitable for a 4kW motor. Well, a motor with 4kW output takes alot more than 4kW input, so I assume what they are really saying is that the drive is only suitable for 4kW output.
I hate when the Chinese do this. It's so dishonest. They advertise at a much higher power output than is actually delivered and you need to read the fine print (if it's available) to see what the real deal is. I've seen the same thing with spindles. That's why I look for current ratings.
Still, your current draw should be well within this range just to get it running and make sure it works.
It would be nice if you could simply borrow the stuff you need to try the vfd that came with it, or take the spindle somewhere where it could be tested. That way you'd know where you stand before dishing out the cash. I'm in a bit of the same boat myself. I bought a spindle and I was assured that it's in great working order, but I won't actually be able to test it myself until I buy some expensive parts.
Good luck to you. If you'd get it resolved, I'd certainly like to hear about it.