Go onto ufile.io, and there will be three lines in the top right hand corner. Press on that, then press "home". There should be a grey box saying "drop and upload files here". Press that and select file you have made and downloaded on FlipAnim. There will be a link to the file. Copy that. Go onto FlipAnim, upload it, and paste link. That's how you make a file!

I use ufile, so it may be different