Let me guide you on what you can do so you'll be able to create an invoice, Hasmik.
You'll get this when you don't have permission to access the areas of the Customers & Sales option. You can check the access given to you by your Company or Master Admin and let them review your access rights to ensure you can create invoices. To edit the access, you can let them follow the steps provided below:
Go to the Gear icon, then select Manage users.
Find the user you want to edit, then choose Edit in the Action column.
You can change the user role from the Roles ▼ dropdown.
You can't edit the Time tracking only roles. Instead, delete them, then add them again with the correct role.
Select the account management settings you want to manage.
Click Save.
Once done, you can sign out and sign back into QuickBooks Online to see if you can already create an invoice.