How to install luci softethervpn in router tplink tl-mr6400 v5

Hello, my router's(tp link tl-mr6400) memory is 8 mb, and I have 1.64 free space to install apps

And I did not find any way to install softether vpn on this router, which requires about 4mb megabytes of free space
I just need the STPP softethervpn configuration, is there a way to customize this app and install it on this device?

I don't think the Image Builder method will release about 4 mb free space
I really need this app on my router, please help me

probably not

get a new router ?