Can't use package from private GitHub repo in shinyapps.io app

[aush]

In the shinyapps.io user guide, it is said that shinyapps.io service supports deploying packages installed from CRAN, GitHub (both public and private repos). But I failed to use my private GitHub package. Here is what I tried:

1. Installed my package locally:
   devtools::install_github("myusername/mypackage", auth_token = 'xxxxxxxxxx');
2. In my app, called require(mypackage)

When I tried to publish it, I get the following message at the end of Deploy:

Error: Unhandled Exception: Child Task 643790794 failed: Error building image: Error fetching mypackage (0.1.2) source. Error accessing GitHub repository myusername/mypackage. Not Found
Execution halted

[aush]

(sort of) solved: figured out that I needed to link my GitHub account in the shinyapps.io admin panel and then add Private Repository Access.