RTL8723BE Firmware module

Hi everyone, I installed Openwrt on my intel celeron laptop that have an rtl8723be wifi card. But in the repository of openwrt, I can't find any package or firmware for this chipset, I tried to 'make' one from 'rtlwifi_new' repo but the result was unsuccesful. 'make' is giving me this error:

make -C /lib/modules/4.14.209/build M=/root/rtlwifi_new modules
make[1]: *** /lib/modules/4.14.209/build: No such file or directory. Stop.
make: *** [Makefile:53: all] Error 2

I'm begginer at programming, there is another way to get that chipset to work? Or any way to fix that error of 'make'?

Thank you <3

Any update to this?
Always joyous to wander dead ends like this one.
This will be hit by every single person who is ever trying to figure out
what to do with openwrt and a RTL8723BE until the end of time.