For those that we like to try by using xe, I did this to create the correct template. I have started from a Debian 10 template, you have to replace with the correct UUID (2 VCPUs):

xe vm-install template=Debian\ Buster\ 10 new-name-label=tempforrunx sr-uuid=7c5212f3-97b2-cdeb-b735-ad26638926e3 --minimal
xe vm-param-set uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a HVM-boot-policy=""
xe vm-param-set uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a PV-args=""
xe vm-param-set VCPUs-max=2 uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a
xe vm-param-set VCPUs-at-startup=2 uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a
xe vm-disk-remove device=0 uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a
xe template-param-set is-a-template=true uuid=fc5c67c2-ee5a-4b90-8e0f-eb6ff9fdd29a

The template is listed when you issue xe template-list.