"White Disk" - means that you are over-exposing Jupiter. Jupiter is BRIGHT - because it is just past Opposition.
Work to backdown the Exposure from 20ms to 10-5ms (using a DSLR we usually are shooting 1/120th-1/250th second to get a decent exposure). Also ensure the Gain is at a reasonable 100-200 level.
Once you have Jupiter at a decent Exposure (even if blurry it should be orange-ish instead of white), then you can work to improve the Focus.
Then, work on Exposure again until you get the most Detail possible (and don't expect all that much Detail in raw captures - that comes after Stacking and Sharpening).
Let us know how this turns out.
