Can I just using the official way to install?

[heronghua]

I installed this plugin by clone this repo into ${HOME}/.vim/pack/vendor/start

But the plugin does not works, other plugin just like NERDTree works fine.

How could I install this plugin without any 3rd plugin manager?

[ShadowProgging]

Manual install (with ultisnips):
https://pastebin.com/QweZS0dD

don't paste the lines with: ```
in ~/.vimrc