Sharepoint migration tool download error

I found the solution at another site:

This is caused by the "ClickOnce Trust Prompt Behavior": https://msdn.microsoft.com/en-us/library/ee308453.aspx

To adjust this, simply change the values in the Registry and you should be able to install the application.

To enable the ClickOnce trust prompt by using the registry editor Open the registry editor:

Click Start, and then click Run.

In the Open box, type regedit32, and then click OK.

Find the following registry key:

\HKEY_LOCAL_MACHINE\SOFTWARE\MICROSOFT\.NETFramework\Security\TrustManager\PromptingLevel

If the key does not exist, create it.

Add the following subkeys as String Value, if they do not already exist, with the associated values shown in the following table.

https://i.stack.imgur.com/3Ri8v.png

On my computer, the values were set to "Disabled" and I have no clue which application did that. I changed the values to default and now everything works again like it should.

Or you can just delete the key "TrustManager" itself and everything is working as well.

source: https://superuser.com/questions/1252575/unable-to-install-clickonce-application-due-to-security-settings-windows-10