Hi Christie,
Sorry to hear that.
Please share the file IDs(downloaded from Adobe Stock) with which you are facing quality issues so that we can check them on our end and let you know.
Also, as you have mentioned that you have downloaded a few vector images(Ai) from Adobe Stock and you do not have Adobe Illustrator to use them, as a workaround you may download the trial version of Illustrator(7 days trial ) and can try to use the files.
You may use this link to download the trial version of Illustrator: Download a free trial or buy Adobe products | Adobe free trials & downloads
Regards,
Twarita