The admin can easily create the customer password in the Magento2 Marketplace extension. For this, the admin will navigate to Customer -> All Customers as per the image.
After clicking the All Customers menu option, the admin can see a complete list of the customers. Select any customer from the list by clicking on the Edit button against the customer for which the admin wants to create/change the password.
Also, the admin can create passwords for the new customers by clicking on Add New Customer button.
On clicking on the Edit/Add New Customer button, the admin will be redirected to the Customer Information page as per the below image.
On the top menu panel, select Reset Password. On clicking on the Reset Password, a link will be sent via email to the customer. The customers can change/reset their password through the link which they will get in the mail.