You must have a base installation of ArcGIS Pro 2.8 already on your machine before this patch can be applied. Key Fixes in Patch 8 (2.8.8)
: Double-click the downloaded .msp file to begin the update. Follow the on-screen prompts and click Finish once complete. ArcGIS Pro 2.8 Life Cycle Status arcgis pro 2.8 patch 8 -2.8.8- download
: Find the ArcGIS Pro 2.8 Patch 8 (2.8.8) entry and click Download (Download ID: 8074). You must have a base installation of ArcGIS Pro 2