how to run custom scripts after project suite Run is completed

We use our build system (Jenkins) to accomplish something similar to what you’re describing.  After execution of the TestComplete project finishes Jenkins runs a “teardown” build step that publishes our results and copies test artifacts to the network.  The “teardown” step runs PowerShell scripts to make all that happen.

Use either PowerShell or Batch file to call the appropriate commands, https://support.smartbear.com/testcomplete/docs/working-with/automating/command-line-and-exit-codes/command-line.html to run your automation scripts. You can then perform other actions once the automation has finished.

Also have a look at Events https://support.smartbear.com/testcomplete/docs/reference/events/index.html to see if this may be able to help.

How are you running the project suite?

I am also working on similar approach using PowerShell to generate html file and to send email, looking for options within Testcomplete to invoke the powershell instead of it as a new step to run the powershell command