You have a few options when adding customers to your instance:
We recommend that you share the Create Account link with your customer base, so they can create their username and password! This will reduce friction for both sides, as customers won't need to reach out if they've forgotten their username or need to reset their password.
To share the Create Account link for your instance, log out of your instance and click on the Create Account button on the login page: 
Another option is to manually add your customers:
The video explains how to get customers and entities into the system. There are three entities: companies, company contacts, and individual accounts. Companies are self-explanatory, company contacts work for companies and must be associated with an existing company, and individuals are people not associated with a company or business.
If your customer base is primarily businesses, or you don't accept orders from individuals, you can set "Allow Personal Account Registration" to No under Order Settings. This will require that users enter a business name to create a customer account.
Finally, if you want to sync your Allmoxy customer/company list to an existing database OR if you want to use Allmoxy internally and not give your customers access to login, you can export your company list from that database, reformat it to match Allmoxy's company import template and import the list into Allmoxy.
By importing customer data, you can clean it up and ensure the information is formatted correctly.
To start, gather all of your data into one Excel sheet and take the time to clean it up. Consider formatting issues such as capitalization, proper addresses, and weird abbreviations. Once you've cleaned up the data, identify the different types of customers you have and delete the ones that you don't want to work with or create an account for. Then, create a few imports by copying and pasting or saving different revisions.
It's worth taking a few extra hours to clean up your data, as it will save you time and effort in the long run. By taking the time to import your customers' data, you'll have greater control over their information and ensure that it's accurate. Ultimately, the most important thing is to execute your plan and use timing and context to your advantage.
When it comes to importing customers and contacts versus letting them create accounts on their own, it doesn't have to be an either-or decision. You can split it up based on the different types of customers you have. For example, you can use some customers as a beta group to work out the bugs and get initial feedback, while ignoring others you don't want to create accounts for yet.