I am assuming this is talking about the https://github.com/ralesi/ranger.el package available from Melpa.
There are several things you can do
Use "!" to run a command. This is made slightly tricky as ranger seems to want to pass the filename you are on to the command, so something like mkdir wibble ; : could be used on unix systems.
Switch to dired mode ...
Not exactly sure what you're asking, but perhaps this will help. Offhand, a guess is that bookmarking Dired buffers is close to what you are looking for.
Dired itself lets you have a Dired buffer that contains (only) a given set of files and directories - from anywhere in your file system. You do this by passing a list of them to function dired. See C-h f ...
Icons in Emacs are provided by the all-the-icons package. I believe that is installed in Spacemacs by default. You can run M-x all-the-icons-install-fonts to get the necessary fonts/glyphs for displaying the file icons and such.
It looks like ranger is an extension for dired-mode and there is an additional package all-the-icons-dired that adds support for ...
Doom's :emacs dired module has a +ranger flag. Enable it and run doom sync on the command line. i.e. uncomment :emacs (dired +ranger) in ~/.doom.d/init.el.
Then ranger will be the default UI for dired.
See this entry in the manual for details on what Doom modules (and flags) are.
It is more reliable to add advice to ranger and deer to try to ensure that helm-find-files is always enabled when ranger and dired are called (as opposed to adding a hook to ranger-mode-hook which is only called once the buffer is created). This should fix the problem of helm-find-files sometimes not being called immediately.
Install https://github.com/technomancy/find-file-in-project (available at http://melpa.org)
M-x find-file-in-current-directory or find-file-in-project-by-selected or find-file-in-project
you got interactive UI to filter candidates. The UI is based on ivy (https://github.com/abo-abo/swiper), so you could input keyword1 keyword2 to tweak the final result (...