Unity will not accept JDK

Hi,

I'm trying to set up for android building and to test on my android device. But no matter what I seem to try, I can't get it to connect to the JDK. I've tried installing Unity 2018.2, 2019.3 and 2019.4 now and in the installs through Unity Hub, I've checked OpenJDK. Every install, the JDK folder stays empty and when I go to add it as a module, it says installing and then seems to be done, but the folder stays empty and next time I check it wants me to download again, so using the HUB is a no go it seems.

So I've tried to go the route of downloading from Oracle directly and linking in Preferences > External Tools. But when I do this, it shows me this error (if the image doesn't show, the error is "Incompatible Java version '8'. Android development requires JDK 8 (1.8) 64-bit.":

So I'm not sure what else to try. The hub doesn't fix it for me, and even if I manually download and set any of the JDK 8 versions from Oracle, it still gives me this error. I don't know how to specifically find 1.8 because when I search for that online, it comes back with JDK 8 and hundreds of different versions: https://www.oracle.com/java/technologies/javase/javase8-archive-downloads.html

So I either need to know which specific JDK 8 on that list 1.8 is so that it'll recognise it, or some other solution. I've been trying to solve for days now and just can't get through.

Thanks so much in advance!