The update process from 1.2 to 1.3, if you want to keep your project files, is not “plug and play” but you’ll find a procedure here: https://store.ambiensvr.com/l/gzwsQt
We strongly encourage you to save a copy of the Unity Project (or git commit+push) before the update, export your AT+V project file first with this package AND with the standard Unity “Export Package” procedure, then install 1.3.
Only with an export from the standard Unity procedure and our exporter I can 99% support you in case of data loss.