In order to configure Magento 2 Guest to Customer Extension:

1. Navigate to Stores > Configuration > Magefan Extensions > Convert Guest to Customer.

Magento 2 Convert Guest to Customer Configuration

2. Enable or disable the extension.

3. Enter the Product Key which is found in your Magefan Account > My Downloads.

4. Enable the Automatic Conversion of Guest orders to Customers in case there a lot of guest orders placed on your store every day and you want the customer accounts to be created instantly after the placement.

5. Choose whether to Assign Order Address to Customer or not.

6. Set the Subscribed to Newsletter option to Yes if you want converted customers to be automatically added to your newsletter subscribers list.

Note: make sure this option is compatible with your GDPR/CCPA/LGPD policy before enabling it.

7. Choose whether you want to Send Welcome Email. If you set this option to Yes, the email will be sent to the user once the guest order is converted to a customer.

Note: we use the default Magento template — New Account without Password, so you can easily customize it. Once you do that, go to Stores > Configuration > Customers > Customer Configuration> Create New Account Options > Default Welcome Email Without Password to assing it.

8. Select what Customer Group you want converted customers to belong to. 

9. There is also an option to Convert All Old Guests To Customers in case you've just started using this extension and have plenty of guest orders you would like to convert at once.

Magento 2 Guest to Customer General Configuration

Once you've finished with all the configurations don't forget to press the Save Config button.

Magento 2 Convert Guest to Customer Extension Save Config