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#1
Where did you download SupportAssist? It may be that you have the wrong version for your model, or it may even be that it's not intended for your Optiplex at all.
Go to Dell Support here: https://www.dell.com/support/home/us...roducts&~ck=mn
enter your service tag and see if SupportAssist is available as a download for your model.
Your My Computer shows only an HP, could be the cause of the error. I have an OptiPlex 755 running the Insider Preview Fast Ring version of Win10 and uninstalled that Dell feature, too old for the latest Operating System.