welcome to the forum,
that is an old version of rclone, and maybe the wrong version based on the cpu of that router.
as rclone is a portable app, does not need to be install.
so can download it from https://rclone.org/downloads/
fwiw, i run rclone on openwrt, but would never use entware.
https://forum.rclone.org/t/aws-hacked-account/37202/41