Follow these straightforward steps to ensure a smooth import:
Navigate to Contacts.

Click Import Contacts (the icon looks like a downward arrow pointing into a box).

In Imports-1 Select Contacts and click Next

Confirm your file format (only CSV file is allowed for import).

Upload your file (CSV files up to 50MB).
Map your file columns to corresponding Contact fields.
If you have non-standard data, create a new custom field.
Or select "Don't import data in unmatched columns”.
Fill in the import details (name your import, create lists, set consent preferences, etc.) and click Bulk Import.
Wait for the contacts to finish importing.