With the current ArcGIS Trial, you will only get 21 days license for ArcGIS Pro, whose license is managed through the ArcGIS Online Account.
If you are looking for ArcMap trial license, I am sorry to say that it is not available with Trial anymore.
I would suggest you to explore ArcGIS Pro.
In case you want to work with ArcMap for personal non-commercial project, you could opt for ArcGIS for Personal Use Program | ArcGIS for Desktop Advanced for Personal Use.
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