Hi Romain,
You should be able to connect MATIC. Just copy the wallet address from your ledger app (or if you use the desktop app create a QR code). Then open the finary app, click on the little plus to add an asset, go crypto wallet, and then either scan the code or paste in the address.
Currently we are not supporting LTC, ADA, XRP and DOT wallets, however you can add your assets manually. Go to crypto, « Enter Manually ». Here you can add the amounts of your assets, and easily track their performance.
Let me know if you have other questions (and sorry for answering in english 
)