syslinux not found

[linreigu]

I'm getting error messages in the linux environment of a Lenovo Chromebook (ARM64). How to proceed?

Erik

bootiso: Command 'syslinux' not found!
bootiso: Should be in package 'syslinux'.
Attempt installation? (y/n)> y
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package syslinux is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'syslinux' has no installation candidate
bootiso: Installation of dependency 'syslinux' failed. Perhaps this dependency has a
slightly different name on your distribution. Find it and install manually.
Exiting...
bootiso: See https://github.com/jsamr/bootiso/blob/master/install.md#dependencies