OpenWrt on WD Mybookliveduo

Hello to all.
I’ve installed firmware 22.03.2 in my nas mybookliveduo, and all appear to be good.
Being a nas, not a router, the most important thing is to show the disk(s) in the lan.
But storage capacity is near to be full, just few kb available.
No space for the important samba protocol.
I’ve seen there is a version (samba4) in the list on the repository.
A contradiction… so many hd space free and no space for a few kb program to add.
Any suggestion?
Thanks in advance

Run gparted on the drive, resize the file system, or use ksmbd instead.