The message "You do not have permission to open the application" is shown when trying to open a downloaded app This seems to be a new issue with Big Sur.
I have &quot;App Store and identified developers&quot; enabled in Security &amp; Privacy, but I've run into a certain app outside the App Store that seems like it doesn't fall under the category of &quot;identified developers&quot;.
When I try to open the app, it tells me &quot;You do not have permission to open the application&quot;. Going into Terminal, however, I can see executable permissions are enabled for the app, just like for every other app.
What can I do to be able to open the app?
In playing with the Triangulator app I found the following issues on Big Sur:

When decompressing the .zip, the application contents didn't retain the execute bits.  Add it back with sudo chmod -R 755 /path/to/app.
Since the application was downloaded by a web browser (in my case) the quarantine bits are set on the decompressed files.  Remove that with sudo xattr -dr com.apple.quarantine /path/to/app.

Once those issues are remediated then the application can be launched.
-Eric