Unable to deploy R-based Shiny app to Posit Connect Cloud - possibly because a required package is a private GitHub repo

,

I'm trying to deploy an R based Shiny app to my free tier Posit Connect Cloud using the Posit Publisher extension in Positron. Deployment fails when trying to install one my R packages from a private Github repo:

2026-08-28T09:24:59+11:00 Initialized empty Git repository in /tmp/download/github-PacificCommunity-masala/.git/
2026-08-28T09:24:59+11:00 remote: Invalid username or token. Password authentication is not supported for Git operations.
2026-08-28T09:24:59+11:00 fatal: Authentication failed for 'https://github.com/PacificCommunity/masala/'
2026-08-28T09:24:59+11:00 Unable to download package masala from GitHub
2026-08-28T09:24:59+11:00 Could not download uncached project dependencies.
2026-08-28T09:24:59+11:00 Failed to publish content: Download of the masala package has failed. Check your manifest.json or renv.lock. error_id=04e8e865-46c0-41de-b217-0d106e47555e

I do not know how to resolve this (my knowledge of Git, Github and app deployment is very limited).
Is it possible to use a package dependency from a private Github repo on the free tier?

Thanks for any help