How to download files to sd card from ftp without rooting

Simple question, but I couldn t find the answer anywhere (all answers requires rooting on android marshmallow because ftp clients doesn t include the permission to write on the sdcard). I have a huge file which is too large to be downloaded on internal storage. So it can only be downloaded on the sdcard directly. It also seems no ternal apps have the permission to write to the sdcard so I cannot use command line tools directly. As the file is huge, I also need to be able to pause and resume downloads.