Downloaded Contacts are saved to ‘Files’ tab in the ‘Send’ menu.
Choose the contact you want to save. Tap 
in the left bottom corner, and select ‘Copy to Contacts’
● Single Contact
In the Contact preview, select your preferred saving method.
● Multiple Contacts
If you select ‘Copy to Contacts’, the list of contacts will be displayed.
By tapping ‘Save’ in the upper right corner, every contact will be saved at once.
If you want to add only some of them, select a specific contact information and add one by one.