That's probably where the problem is.
Type the following
wget https://download-cdn.resilio.com/2.6.3/Debian/resilio-sync_2.6.3-1_armhf.deb
sudo dpkg -i resilio-sync_2.6.3-1_armhf.deb
This will override the previous installation. Then check from the web interface that Raspberry Pi is also running 2.6.3