to get in sadpanda you have to download the chrome extension on their github, you just have to download, extract, go to the chrome extension menu, you activate developer mode on (up right corner), and then you hit extract extension or something like that, you choose the sadpanda extension folder, and then you're up to go to the page.
However, to enter exhentai you still have to make an e-hentai forums account, after you make it you have to wait exactly a week or 7 days for it to work, i know it's a really long time, but it really pays up since whenever there's not leaked stuff on kemono or in any other page you can bet it's on exhentai, just like this JADF leak. After you wait the 7 days you will be able to log in with your account (that if you put incognito). If you don't wait the 7 days the page would just put you again in the log in menu lol.
You also have to delete the cookies to try to get in, i don't know how that works but delete them after you install the extension so you don't have errors (you can add another cookies manager extension then delete all sadpanda or exhentai related URL).
and yeah, the URL is actually exhentai.org but it has that security of the extension and the 7 day long account.