So what do u need 5/8" arbor or 1/2"? Some pads like with eastwood say they fit both size shafts as the the hole is not reinforced. I was looking at the website seen a lot of things out of stock and also some pretty exorbitant pricing.
My advice order some things from Amazon if you need starter stuff and to get your feet wet.
A set of mixed pads firm spiral sewn (different ply) for heavier cutting and then a soft loose for final polishing...
Something like this
https://www.amazon.com/dp/B07K8QX5CF/?tag=atomicindus08-20
I use some like this on my 6" bench grinder though they are 1/2" arbor. Worked well for me.
https://www.amazon.com/dp/B07TVMJD1K/?tag=atomicindus08-20
Mixed compounds are sold separate
https://www.amazon.com/dp/B079Y8TTNM/?tag=atomicindus08-20
Once you know what work best in your application you cam buy just the ones you need most.
Cheapest way to get compounds IMO is one of those little box kits that come with cloth polishers , you get your basic compounds for steel, aluminum and chrome and some even maybe for plastic. It worth having the small 1/4" shank wheels and fobs to get into tight or awkward spots. You use a hand held tool...collet die grinder, pistol type polisher tool like the Milwaukee 2438 or even just a plain ol' hand drill for them I bought a HF kit last summer I just recently used I think it was only like $12 on sale back then.
https://www.harborfreight.com/14-piece-aluminum-polishing-kit-98707.html
For something like the 2438 tool you can get roloc style flat felt pads to fit the standard backing plate too.
If you weren't overly concerned about using 8" wheels and 6" will suffice something like this would be totally cheap and simple for your needs to get started doing something without a big investment
https://www.amazon.com/dp/B001QXI9VW/?tag=atomicindus08-20