Why can't JDownloader 2 get Captcha pop ups to appear when downloading a file from RapidGator?

Yes, you can download 4K YouTube videos, although it is recommended that you download a bit lower quality video than 4K.

Yes, you can configure JDownloader 2 to cleanup the list of downloads one they have been downloaded. To do so, follow the steps given below:

• Tap on Settings and choose Download
• Go to the Download folder
• Under the download management, search for Remove finished Downloads
• Choose the option that you find most suitable.

JDownloader has the capability of creating a subdirectory for each file. To stop it, follow the steps given below:

• Open the Settings
• Tap on Packagiser
• Deselect the predefined rules that you wish to be excluded.

To disable ads in JDownloader, follow the steps given below:

• Launch JDownloader
• Click on Settings > Advance Settings >Filter Settings
• Search for the appropriate keywords and then disable them accordingly.

Yes, there are many download managers which are Ubuntu compatible, such as:

• JDownloader
• Kget
• uGet