in case you do not find what you are looking for, please allow me to give some hints. The left hand menu is the best way to navigate through the IAJO web site. You look for:
The organists are filed under the countries of his/her origin, select the country in the section "Jazz Organ Scene", you will see a list of organists in alphabetical order of their surname. If you do not know the country, please use the search function (in the menu "Search & Find"). Example: You are looking for Larry Young, you will find him under "Jazz Organ Scene" -> USA U-Z.
Albums and CDs are listed on the organists' pages in the order of recording/release dates. From 1996 onwards, there is also a section "New Releases". Choose the year and you will see a list of albums in the order of their head artists (that need not necessarily be the organist). Here, each album has its own page with a small cover picture. The albums are filed under their year of release. If you do not know it, please use the search function. Example: You are looking for Tony Monaco's "Groove: Blue", you will find it under "New Releases" -> 2015.
See the section "MP3 Samples". All music files offered on this web site are authorized by the musicians and/or record companies. Some are offered for streaming only, not for download. You will find a list in the order of the organists. You can listen to the music by clicking on the corresponding speaker symbol. Maybe the player does not start automatically. Either your browser does not support autoplay or you have to enable autoplay in your browser's options. Also it can happen that your browser does not allow playing audio or video files at all due to security options. You have to explicitly allow this feature. Have a look in your browser's options.
During a test period, I have installed Spotify links. You can listen to complete albums on Spotify (if available), it is completely free of charge. But you have to take some steps to start with.