Bootdisk error

I want to generate bootdisk.
I installed rubygem-foreman_bootdisk

got bootdisk in setting but when I try to render some boot disk :

Problem:

Error

Failed to render boot disk template: ERF42-5290 [Foreman::Exception]: Unable to find template specified by bootdisk_host_template setting

Expected outcome:
an ISO disk !

Foreman and Proxy versions:
3.5.2

Foreman and Proxy plugin versions:
rubygem-foreman_bootdisk-21.0.3-1.fm3_5.el8.noarch

Distribution and version:
RHEL 8.7

Other relevant data: