Hi Stephanie, thanks for reaching out! What type of table are you trying to import this source into? If it's a people table, then you should be able to add your LISN source to it. Otherwise you will have to create a new table.
Yes, the Sales Navigator search in Clay is still limited to 2,500 records maximum. However, your import limit for the find people/companies/job search is 50,000 with your pro plan.
Let me know if you have any other questions! ๐