So I made a previous guide on how to download the initial games files so here is another one for downloading patch files. This guide aims to help with downloading the patch files for an already installed version fo BDO. Hope they help!
Step 1: Let the launcher do its thing until it starts downloading files with .PAP extensions at the end of them. At that point close the launcher.
Step 2: Navigate to the Black Desert installation folder and look for a file named update.log and open it in a text editor.
Step 3: In update.log, look for a bunch of INFO lines with the current date (not the date when this post was written, but the date when you completed Step 1). Then look for a line that has CDN URL along the line (capital letters or not). There should be a URL on the same line so copy that URL (something like http://naeu-o-dn.playblackdesert.com/UploadData/)
Step 4: Now open another file in a text editor and paste the URL you copied. Then add /patch/ to the end of it (including both forward slashes). The URL should now look something like http://naeu-o-dn.playblackdesert.com/UploadData/patch/
Step 5: Now go back to the update.log file and look for an INFO line with the current date (date when you completed Step 1) and latest version on it. Note the number on this line (such as latest version : 2179). Then also look for an INFO line shortly under that one with client version on it. Note the number on this line as well (such as client version : 2172). Finally also look for a line shortly under those with download file count on it. This should equal the difference between the client version and latest version numbers (such as download file count : 7)
Step 6: Now you can put together the total link for each patch file for the update that your client needs. Simply start one number above the client version number (e.g. if client version : 2172, start at 2173), then add .PAP to the end of it (the case is important). Full URL should look something like http://naeu-o-dn.playblackdesert.com/UploadData/patch/2173.PAP. Then for each update file, simply add 1 to the previous number until you reach the latest version number (e.g. the final patch link should look something like http://naeu-o-dn.playblackdesert.com/UploadData/patch/2179.PAP). Note that the first patch file starts one number above the client version number but the final patch file is equal to the latest version number.
Step 7: Then whenever all the files finish downloading (there should be an amount of files equal to the download file count number), move those files to the folder patch_temp in the Black Desert installation folder. Then simply reopen the launcher and let it take care of the rest. And that's basically it!
P.S. the final URLs for the patch files are case-sensitive; so if you keep running into an HTTP error, check the URL both for equal cases and equal text, notably with the extensions.