Baixe a subpasta do github
svn checkout https://github.com/user/repo/branches/mybranch/folder
Or just use: https://download-directory.github.io/
TL;DR
svn checkout https://github.com/user/repo/branches/mybranch/folder
Or just use: https://download-directory.github.io/curl {url for downloading zip file} | 7z a -tzip {project name}-{branch name}/{folder path in that branch}