If you really did everything right, then you should be able to start the mod from within the game.
After you launched Sins, go to Options, there on the sidebar you should se a Mods part. Click on it.
In the right main screen you will se two columns, One labeled as Available mods and the other as Enabled mods
Look for Ascendancy-Sins within the Available mods collum, left click on it and press Enable mod to the right of the columns.
Then if you click on the Apply changes Ascendancy should start up. Just make sure you have LAA enabled
If you use the CD version, the game will also keep this setting and will start Ascendancy next time when you start the game. For steam version, I am not sure.