I'm a free DG account member since several years, but sometime I upload some drivers what I think are hard to find...
I download some drivers too, but no problem with limits to my free account.
I don't understand how credits works with DG.

To my knowledge, there are no credits given for uploading a driver. This has always been on a basis of helping each other. Are you saying there is a page somewhere that offers credit for uploading drivers? If so, please point us to that page.