Can anyone tell if Portal for ArcGIS can be authorized using Field Worker license?
What do you mean by "Field Worker license"? Are you referring to the one of the new ArcGIS User Types options?
An ArcGIS User Type is a combination of identity, capabilities and apps that align with the needs of typical members in an organization.
FYI, Portal for ArcGIS is a component of ArcGIS Enterprise. Depending on the ArcGIS Enterprise edition and level, a set number of named users is included - which can be used with Portal for ArcGIS.
ArcGIS Enterprise Functionality Matrix 10.6.1
(see page 10)
With the new ArcGIS User Type options, level 1 named users are Viewers and level 2 named users are Creators.
You don't use the named users to "license" Portal for ArcGIS - a separate and different license file is needed to install Portal.
Hope this helps,
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