Can you please advise why download button is not working?

I enabled the Download feature while creating my book, but I can't download anything after converting, can you please tell me what I can do to make the Download work?

While using Flip programs, to make the Download button work, you need to enable the Download feature and insert correct Download URL in Tool Bar Settings->Download Setting.

If you want people to download your book to read offline, you can output exe or zip format book first, upload online, and then back to the Flip program, Enable the Download feature, and input the exe or zip link as Download URL, then build HTML format book and publish all output files and folders online again, then when people click the Download button, they will download related EXE or ZIP format book directly.

More details about sharing files online here.

You can also allow people to download other related files by clicking the "Download" button, like PDF document, PPT presentation, Video, Images and so on.