Make sure you are using the latest version of the extension. You can find the version logs at https://www.huntbee.com/abandoned-cart-emails-automated-manual
The latest stable version for this extension is 3.x.x
In case if you have not followed the installation documentation properly and you have broken the website while installation, then follow the steps given below to fix it.
Website broke after installation, not able to access admin
First of all, it is necessary to understand why the website broke. The website breaks when the installation is not completely done. The extension uses ocmod to place the script to some of the system library files and when the database table is not installed, the script will fail to connect to the database table that it is looking for. The tables are installed in the database only when you click on install button of the extension at Extensions > Productivity App > Abandoned Cart. So as soon as you upload the extension via extension installer you need to install the extension here and then only you can refresh the modification. If the modification cache is refreshed before installing it will break the website and you will not be able to load your admin or store front page.
If you have broke the website and you are not able to access the admin, do not worry as it is not that complicated as it looks. You just need to get back access to the admin to fix this and to get access to your admin, you need to go to your file manager via cpanel or filezilla and go to location of the modification storage. You need to delete all the folders here (admin, catalog, system).
For opencart 2xxx, the location is mostly system/storage/modification/ . For opencart 3xxx, the location is dependent on your storage location specified by you during installation.
Make sure you only delete the modification files and not the original files of the opencart
Once you clear/delete all the modification files, you will be able to access the admin and go to extension > modification. Disable the modification ABANDONED CART EMAIL.
Now you can refresh modification, as the abandoned cart extension is disabled in the modification.
You can now go to Extension > Productivity Apps > Abandoned Cart PRO > click install.
Setup the extension and click on Save button.
Once extension setting is saved, you can enable the Modification (
Extensions > Modification > ABANDONED CART EMAIL ) and refresh modification
Test the extension by adding products to cart.
In case if you are not able to fix it yourself, submit a support ticket in https://www.huntbee.com/get-support