• Create customer
  • Create user
  • Apply permissions to the user
  • Add website user to the customer
  • Create and submit invoice
  • Log on as the user

Create Customer

In your ERP Next dash, go to : Selling>CUstomer>Create new customer
Enter details like name, type and email etc - once saved this will create a contact in CRM

Create User

go to: Users and Permissions>User>Create new user
Enter email, first name and last name, uncheck “send welcome email” - once saved this will create a contact in CRM - by default a new user will be type “website user”

Click on the created user and add a password under “change password”

Apply permissions to user

Click on the user created and scroll down to roles - check the “customer” checkbox - save.

Add website user to the customer

Go to: CRM>Contact and pick the website user created - scroll down to “reference” and add row
Link document type is “customer” then pick the relevant customer - save
To check this
go to:Selling>Customer>pick the customer and scroll down to “Address and contact” - you should see that the webuser contact has been added.

Create and submit invoice

Note: This assumes you have created at least one item to add
Create the invoice using:
Selling>Sales Invoice>New - Pick customer, add items and save - submit the invoice.

If you now log on as the website user go to:
My account - click on invoices in the left sidebar - You should see the created invoice!
Note: the only options by default are to read OR print



Find below reference / source link 


https://discuss.erpnext.com/t/solved-customers-ability-to-view-their-own-invoices/60351/10