Follow the 5.2 onwards integration instructions in Integration Pages which consists of these steps:
You can determine that you successfully completed the upgrade by checking the SDK version in Play to Validate step and confirming the correct Editor version (ie: u5.2 or u5.3) is displayed in Validator.
If you did any existing Advanced Integration previously, you will also need to update the namespace and the calls to use the 5.2 and up syntax. Follow 5.2 onwards Advanced Integration instructions to update.