Installing paid plugins and themes from themeforest and envato

It`s this theme:

It is not nessesary for me, that I can install it with composer. It would be cool, but I think it`s difficult to support that, because you need to be logged in at envato to download it and so on

My question is more: What is a good way to include such themes or plugins in an bedrock environment which uses composer?

What I now did is:

Theme:
web/app/themes/_no_composer/aperture

Plugins:
web/app/plugins/contact-form-7 #composer managed plugin
web/app/plugins/_no_composer/revslider
web/app/plugins/revslider -> symlink to _no_composer/revslider

Is this a good way, what problems could it cause?