I have student license for ArcGIS Pro, I want to use AGWA extension tool. AGWA conducts hydrologic modeling and runoff assessments at multiple temporal and spatial scales.
https://www.epa.gov/water-research/automated-geospatial-watershed-assessment-agwa-tool
I have an issue that I can't install this add-in in my ArcGIS Pro 3.2.1 version
Looking at that link, that add-in was built for ArcMap, not ArcGIS Pro. That is why you are not able to install it.
I would recommend contacting the people listed at the bottom of that page for information on a potential version that runs with ArcGIS Pro.