Adobe have not said there is a limit on total files. But there are limits on the number of submissions you can have waiting to be accepted. The number of files is a secret, and likely to change, so people can't game the system. My personal recommendation is to submit no more than 10 images if you are a newcomer (that is, submit 10, wait for accept/reject, then submit more). Newcomers often see a lot of rejections, as they learn what Adobe wants, and if Adobe had to reject 100 images at once, they would probably block you forever for wasting their time. The time in review varies, but for AI and illustrations it may be several months. This delay was caused by AI users who submitted unreasonable amounts of generated images, mostly of very poor quality. (AI generally needs a lot of time consuming checking and correction to meet Adobe's standards, so generating thousands in a short time, of acceptable quality, would be impossible).
Good luck with your future in stock!