You'll have to define the entrypoint in traefik's static configuration. The only default one is http on port 80 (checked on v2.4).
https://doc.traefik.io/traefik/routing/entrypoints/
This won't work as you're expecting:
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="21"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65500"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65501"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65502"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65503"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65504"
LABEL traefik.tcp.services.ftp.loadbalancer.server.port="65505"
You're just redefining the same label over and over.
I'm pretty sure for this to even have a chance of working you will need an entrypoint,router and service for each passive port you are using as well as port 21 for each too. It will be a lot of labels.
/aside Why FTP ?