How do I start a process from a URL (in an email) using processModelOpaqueId and cacheKey or some other way?

Hello,

We have a need to place a start process link in an email to end users so that the users can go directly to a process that has not yet been started from their email notification.

I have tried the following and it seems to work for the user that generated the link; however, if a different logged in user tries to use the generated URL it gives the An Error Has Occurred The process does not exist, has been deleted, or you do not have permission to start it.  Pink Box.

a!localVariables(
  local!startProcessLink: a!startProcessLink(
    processModel: ri!processModel,
    processParameters: ri!processParameters
  ),
  
  local!processUrl: cons!CONSTANT_FOR_BASE_URL 
    & "/start-process/"
    & index(local!startProcessLink, "processModelOpaqueId", null)
    & "?parameters="
    & index(local!startProcessLink, "cacheKey", null),
    
  local!processUrl
)