The number of accounts you can add to Tracking depends on the subscription level you have.
On a Free level you can track only your Instagram account. In order to do that you need to confirm your Instagram account.
On Basic plan you get a possibility to track 5 accounts (plus 1 free slot for your confirmed Instagram account).
If you need to track more than 5 accounts, no worries, we can find an individual solution for you as a part of Pro plan. Please contact our sales team to go forward firstname.lastname@example.org
These are the limits on the number of accounts you can track simultaneously. You can always delete any account from your Tracking list and add another one instead.