It's not free.
> Larger runners are only available for organizations and enterprises using the GitHub Team [$4 per user/month] or GitHub Enterprise Cloud [$21 per user/month] plans.
> Larger runners are only available for organizations and enterprises using the GitHub Team [$4 per user/month] or GitHub Enterprise Cloud [$21 per user/month] plans.
> We expect to begin offering Arm runners for open source projects by the end of the year
side note: I find it mildly annoying that it's no longer "ARM" but "Arm"