gcc : permission denied after new installion

It's a new installation on Deepin OS. I wanted to install gcc-8.3.0 on my computer.

I've done this manually cause it only propose me gcc-6 with apt. So I've installed all the depedency (GMP, MPFR, MPC, isl...) then I've proceeded to gcc. I've followed this tutorial : https://archerfmy.github.io/2017/04/12/How-to-switch-your-gcc-g-version-in-ubuntu/ to add the new installation. But now the problem is that I can't use gcc anymore.

gcc 
zsh: permission denied: gcc

which -a gcc
gcc not found