Is it possible to download an assetbundle using FTP?
Yes it is possible.
1-First crate your asset bundle through AssetBundleExport editor script.
2-upload that AssetBundle on your ftp server using an empty folder.
3-Then write one crossdomain.xml file which includes following text which in image shown.
and save it and upload on your ftp
4-attach BundleLoader script to empty gameobject in your scene.
5-give a path of your ftp in string like(ftp://shanky:firstname.lastname@example.org/AssetBundle/myAssetBundle.unity3d) And store version as a 1.
6-Then done just hit play button you’ll get your asset on view-port.