This was a temporary problem, we're sorry about that. Problem solved now, FYI.
See: https://support.abp.io/QA/Questions/3171/Nuget-package-restoration-issue
BTW your ticket was refunded.
Thank you
/src/apps/auth-server/src/Vantage.AuthServer/Vantage.AuthServer.csproj : error NU1301: Failed to retrieve information about 'System.Text.Encodings.Web' from remote source 'https://nuget.abp.io/[OUR PRIVATE KEY HERE]/v3/package/system.text.encodings.web/index.json'. [/src/Vantage.sln]
I even attempted to create a new micro-service project using ABP Suite and that also experienced the same issue.