To import contacts from a csv file into Office365 contacts follow the following steps:
1) Select "People" from the main navigation bar
2) Select settings (gear icon) and "Import Contacts"
3) Click on "Browse" and select the csv file you want to import and click "Import"
This will import the contacts into your Office365. As long as this account is linked to your Covve account, the contacts will be synchronized with your Covve account and then deduplicated and enhanced.