I would suggest a boot camp - the exam changed in July 2017. Anything you find on line now will probably be for the old exam. there is something like 2k ISSAPs in the world, so not that may posts. Although the old material should cover you, it did not work out that way for me. The level of details is far more in depth than the CISSP. Good Luck !
I've thought about CISSP-ISSAP as well, and not to throw a wet blanket on it, how much value does this really have? I've been a security architect for about 8 years and can't remember ever meeting anyone with this. Would potential money and effort be more valuable to focus on something like sabsa training?