Vignette not installing or missing

I've created a package to use internally in our small company. When I install on my PC the vignette installs and I can see it with the following command:

vignette(package="TaxAwareAA")

I emailed the tar.gz file to my colleague (who is new to the company and R) and walked him through installing it via RStudio's Packages / Install from Package Archive File. The package installs. During the installation there was even a "Vignette installed" message. But the vignette is not there both according to the command above and our browsing the library.
Any ideas why the vignette is missing and how we could install it? Thank you. Not sure how to make this reproducible (could put the tar.gz file on Github).

Did you try to create a copy of the package on github?

You can try this tutorial:
http://kbroman.org/pkg_primer/pages/github.html

I don't know if you want to keep the package private. In this case you can pay for the github private version or you can use other platforms like bitbucket. If you want to do public you could send to CRAN and there they will help you to check all the problems.

Here is a link to the Github repository

Thank you.

When I install a package, even from github, it is located in the R-library folder. But after installing your package I can't find it in that folder.

How did you created the package in github? From Rstudio or another way?

How did you create the tar.gz ? Did you build the vignette before ?

If you used devtools::build(".") in you :package: source directory, it should be ok.
See this about vignette if not already know.

VIgnettes are not always build by default and could not be present at installation if not built before. It is why I asked.