hello nova-s, please don't waste your time! This standard tutorial has never worked with Acronis ISOs. At least not with PCs with normal bios. It may work with PCs with (U)EFI, but as far as I remember, it depends on the Acronis version. All in all an unsuitable tutorial. Better you use e.g. YUMI with the advantage you can store more ISOs on one USB-stick.
I have seen that message. You have to try multiple times. Instead of pressing any key, reboot/restart the computer. Also, if you have made changes to the BIOS, sometimes you have to reboot/restart at least twice for the new settings to take effect. The bootable ISO uses the Linux environment to boot. It can take some time to boot, up to a few minutes, depending on your computer. If you see a blank screen while booting, say more than five minutes, reboot/restart and press F11 while Acronis is booting. Type vga=ask at the command prompt, and choose the resolution closest to your computer screen. You can also modify the boot file after unpacking the ISO. If this sounds like rocket science, your best bet is to use WinPE or burn the ISO to CD/DVD.
And don't forget to light a smoke candle to the right of the monitor... ... and one to the left of the keyboard, otherwise this won't work. ROTFL Sure, and we can develop the world new! How many guys tried to add the special Acronis-CD to there boot-stick without success? Acronis is based on a special version of El Torito. The first useful sentence in the post. Both ways work right away.
Press the button universal restore in Acronis and the download-page in your language will be opened...