Well that Teledisk image file is perfectly fine, I can't imagine why you weren't able to write a floppy out of it.
Since this disk is bootable though, here is an .IMA file that you should be more comfortable writing it with something like WinImage (on a 720KB 3.5", unless you modify it):

If you still just want the individual files, just say it. I believe a disk image is the way to go with this.

Thank you. I'll have another look into it soon. I guess the problem might be that I write the file to a 1.44 MB disk (using an USB disk drive on my modern pc) and then ask Teledisk to write the image from the 1.44 MB to a 720K disk?

You mean you transfer the image file to some computer capable of running Teledisk using a HD disk? This isn't of course any problem, but I'm not sure I understood you correctly.
Anyway, you can even write it directly on your modern PC now that you have an .IMA file. Just make sure that your USB floppy drive writes DD disks, not all can.

Yes, I use an older system (AST in my signature) to write image files, but the file first needs to be downloaded with my modern pc. Thereafter I need to transfer the file to a disk (with my USB disk drive) and then I can read it in my old AST. It's probably not the most efficiënt way but that's all I can do at the moment. I don't have any experience with Teledisk (apart from my recent attempts), all I know is WinImage but I use that very little, I don't have much experience with creating bootable disks, so I make a lot of mistakes 😊 Anyway, I'll try it again soon, I'll let you know. Thanks.

Thank you so much, the image file in .IMA format works fine.

Good to hear!