Your export still works
Mint's transactions.csv carries the columns Footnote needs: date, description, amount, transaction type, category, and account name. The transaction type column carries the sign, which is why a naive import of a Mint file often shows every credit as a charge. Footnote reads it correctly.
Open Footnote settings, choose Import history, pick Mint, and upload the file. Years of history land against your current connections, matched by shared transactions rather than by account name.
Why the free replacement never quite arrived
Mint was free because it was advertising-supported, and the incentives that come with that are part of why it stagnated. Most of what replaced it is a subscription, which is a more honest trade but leaves nothing free.
Footnote keeps one institution connected free, with the full feature set on it. The paid tier is for additional institutions, investments, and debt tools.
What is different from Mint
Every number shows its work. Open any figure and see the transactions behind it.
Money shared with a person. Split a bank charge with someone, keep a running balance, and settle with the source attached.
Equity compensation. Vest schedules, cost basis, withholding, and concentration, from the documents your employer already gives you.