Modern gear on Goodwill sells for too much, usually. If you're looking at this lens, be prepared to bid at least $250. I wouldn't be surprised if it sold for $300. It looks good in the pictures. If I was in the market, I'd consider it, but not for $300.
That's for a lens with zero provenance. There's no one to testify about its past use or a knowledgeable inspection. The seller knows nothing and there's no one to ask. Everyone involved in the sale is pretty much blind about the merchandise. And yet, newish gear gets bid up on Goodwill.
On the upside, if you buy from Goodwill there's no doubt you'll receive what was in the pictures. No scams. Shipping runs $15-20.
It would be easy to find a good copy of this lens on Ebay for $250, less if you're willing to wait for a deal or accept some known imperfections. This Goodwill lens will sell for that price too, and it's probably fine; a decent lens for a decent price from a reputable seller. But if you're specifically looking for a used RF 24-105 f/4-7.1, you can shop around and probably do better than Goodwill or at least find somebody selling a lens that they've worked with and can tell you about.