For me it worked to use the distinquished name of the OU for example:
Set-LapsADComputerSelfPermission -Identity "OU=Company,DC=exoip,DC=local"
You can find this if you right click the OU you want to use LAPS for and click on properties. There you have to go on attribute editor. The first thing there should be the distinquished name. Maybe this helps you if not I dont know another solution.